What Is A Quicksort Algorithm?

graphic illustration of data files being sorted

The Quicksort algorithm is a useful way to sort through data, available in a number of languages, such as C++ and Java. For many coders, quicksort is indispensable, and almost every programming forum cites quicksort as one of the most efficient sorting algorithms available.

But what exactly is the Quicksort algorithm and how does it work?

Recursion: Key to Understanding the Quicksort Algorithm

Quicksort is relatively simple, but a user needs to understand two key concepts in order to comprehend the algorithm as a while. The first concept is recursion, which is used in nearly all dynamic programming languages. Simply, recursion allows a computer program to perform the same task over and over again with different elements or variables.

For example, in JavaScript (which is a dynamic language), the computer program can check to see if an array element is higher or lower than five (for example). Then the computer program can be set to recursively check each element in the array (which is essentially a list), and report whether that array element is smaller or larger than five. This technique is more useful than having the user type every item in the array and sorting through them that way. As usual, Geeks for Geeks has a thorough explanation of quicksort.

The Divide-and-Conquer Strategy Explained

What happens though, if the list is large, containing hundreds and hundreds of entries? Even with recursion, the process will take too long if the computer program can only check one number at a time. That is where the “divide-and-conquer” strategy comes into play. When divide-and-conquer is used by a sorting algorithm, one array element is chosen as a “pivot”. This pivot is then used to break the array up into multiple sections, otherwise known as partitions. Once these partitions are created, then the computer program begins using recursion on each section of the program simultaneously. 

An Example of Divide-and-Conquer

An example of this concept in action is as follows:

An array is created with the numbers 3, 6 ,2, 25, 12, 90 and 47, and the algorithm is tasked with sorting these elements in numerical order and returning a completed list. The program designates the data element “25”as the pivot, creating two partitions. The first partition consists of the array elements “3, 6, and  2”. The second partition consists of the array elements “12, 90 and 47”.

The number “25” essentially is placed in the middle. Another way to explain is that the number “25” is untouched by the algorithm. Then, the algorithm simultaneously begins sorting both partitions, with the results being “2, 3, 6, and 12” in the first partition, while the second partition would be “47 and 90”. Meanwhile, the pivot (or 25) would be in the middle.

The results are then combined into one large array, which would appear as “2, 3, 6, 12, 25, 47, and 90”. While this example is concerned with numbers and arrays, due to their association with quicksort, this strategy is not limited to numbers or even sorting. Any large task that could feasibly be divided into a number of small sections can be processed using divide-and-conquer. Divide-and-conquer is not limited to quicksort and many sorting algorithms take advantage of this technique.

One notable feature of Quicksort is that no action is taken in the combine step, unlike certain other algorithms such as mergesort. All of the work of sorting is done in the divide-and-conquer steps, and so the combine step simply puts the list back together. While perhaps not useful for the programmer to know, it is an interesting bit of trivia to learn, and also allows a skilled coder to tweak quicksort for best performance.

There are many reasons to use divide-and conquer, but one obvious gain is if the computer program has access to multiple processors. Each partition can be assigned to a different processor and so many performance bottlenecks can be avoided. More information on quicksort and how it works can be found here.

Why Use Quicksort?

While knowing the concepts behind quicksort is useful, it doesn't explain why we should use Quicksort in the first place, considering other algorithms, such as mergesort, appear to be just as effective on paper.

This is a case where simply looking at formulas or statistics may be misleading. While the worst-case running time of quicksort is as slow and inefficient as selection sort's or insertion sort's running time, the average-case running time is as good as merge-sort's running time, which is O(n² ). Already this running time is quick, and would make for a good reason to use quicksort.

What makes quicksort so useful is that the constant factor represented by the O factor actually is quite good, generally enabling quicksort to match or even be faster than mergesort for real world applications, if the coder is careful in ensuring the optimal conditions for quicksort to operate with optimal efficiency.

Being Smart In Using Quicksort

How do we ensure that quicksort is working at its optimal speed? The answer lies in the partitions. If the programmer is careful in choosing the pivot, and both partitions are of equal size, then the algorithm is much faster at sorting than if the partitions are of unequal size.  Read more about it in this article.

If the partitions are of unequal size, the speed advantage inherent to quicksort is lost and the logarithm may be even slower than a stable sort such as mergesort. Careful coding is necessary to preserve quicksort's speed advantage.

For almost any type of sorting that doesn't need to be stable, Quicksort probably would be the first and strongest choice of the veteran programmer. What is stable sorting? Well, that's another question and one that should be answered if the user is to truly understand the capabilities of Quicksort.

Stable and Unstable Sorts Explained

A stable sort essentially tries to keep the order of the original list to be sorted when possible. For example, let's just say a stable sort algorithm, such as Mergesort, had the following array elements to sort alphabetically by first letter:

stable

space

arrow

zebra

A stable sort algorithm would return the following result:

arrow

stable

space

zebra

In other words, the algorithm would respect the original order of the entries “stable” and “space” and not alter the order. This is an example of a stable algorithm.

Meanwhile an unstable sort may or may not respect the original order, so the return could either be:

arrow

space

stable

zebra

or it could be:

arrow

stable

space

zebra

Please note that neither return is incorrect. If what the programmer requested was to create an alphabetical list by the first letter of the word, both returns are legitimate. However, if the user needs to respect the original order of the array or list when appropriate, then this feature of Quicksort could be seen as a drawback.

However, if the user decides to use a stable sort, certain advantages inherent to unstable sorts are lost. Unstable sorts tend to use much less memory than stable sorts, while still being just as fast. Even better, an unstable sort will generally be easier to code than a stable sort.

Quicksort: A Flexible and Useful Algorithm

But suppose you need a sorting algorithm that is more stable than classic quicksort, but still retains quicksort's speed? Well, that's fairly simple. The quicksort algorithm can be coded to exhibit the same traits as a stable sort algorithm. While this solution does require some skill in coding, the rewards are obvious. When the stability of a stable sort and the memory use and speed of Quicksort are combined, the results can undeniably be effective.

With careful planning and proper coding, quicksort is an undeniably effective sorting algorithm for C++ and Java users. Considering its relative ease of coding and hefty speed advantage, there should be no question as to why quicksort is so popular. As long as the coder understands that the algorithm produces unstable sorts and the partitions must be roughly equivalent, quicksort is a powerful tool. Every coder in need of a sorting algorithm should try it today.



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What is a Selection Sort Algorithm?

programmer figuring out the selection sort algorithm

A Selection Sort Algorithm is one of the simplest types of sorting algorithm currently in use. However, if the coder doesn’t understand the concepts behind the algorithm, even this simple tool can cause issues. As with any program, both positive and negative issues must be understood before the algorithm is used successfully.

Why Use a Sorting Algorithm?

First, let’s examine the situation in which the coder will need a sorting algorithm. When the coder is confronted by a list or an array, and needs to put it in a particular order (for example, when a list needs to be placed in alphabetical order, or when an array needs to be placed in numeric order), then a sorting algorithm must be used in order to generate the sorted list that the coder needs.

The coder may choose from a number of algorithms which would help in this situation, and each algorithm has both benefits and drawbacks. Selection sort is an algorithm of this type. However, selection sort is not used very often, for a number of reasons.

Selection Sort—How Does it Work?

First, let’s examine exactly what type of algorithm the selection sort is. A selection sort algorithm is an in-place sort, which means that it does not partition a large list or array into smaller pieces and then work with them simultaneously. In other words, the selection sort algorithm does not use divide-and-conquer, unlike a number of other sorting algorithms, including quicksort.

Instead, selection sort runs two loops at the same time. The first loop consists of numbers that the selection sort has yet to sort, while the second loop consists of numbers that have been sorted. The first loop goes through all of the numbers in an array or list and then takes the lowest number (or

number with least value) and then places it in the second loop. These actions are repeated until the list is sorted.

Selection Sort– Examples In Action

Here is an example list which currently is unsorted:

45
23
2
56
90

The selection sort process will place the above list in a group and then look to see which entry has the smallest value. In this case, that entry would be “2”, so the algorithm would place the 2 in the second loop.

First Loop Second Loop
45 2
23
56
90

Then the algorithm would check the first loop again, looking for the entry with the least value. In this case, it would be “23”. So, then the algorithm places the entry as the next number in the second loop.

First Loop Second Loop
45 2
56 23
90

This process is repeated until the first loop simply runs out of entries. Then the second loop is returned as sorted.

Problems with Using Selection Sort

As is fairly obvious, there are a number of drawbacks using this method..First, the selection sort algorithm must plod through each entry one at a time. This shortcoming ensures that selection sort is much slower than algorithms such as quicksort or mergesort on long lists. If a speedy result on a long list is the coder’s aim, selection sort should be avoided.

Also, the classic use of selection sort is inherently unstable, meaning that the list that it creates does not preserve the order the list items or array elements were originally listed. This trait may be modified by a knowledgeable coder, and so selection sort may be stable, depending on the coding implementation.

In terms of complexity, selection sort is O(n²) in both average and worst-case scenarios. Although O(n²) isn’t very fast, there is very little variation between the fastest scenario and the slowest scenario, which is a positive feature.

Reasons to Consider Using Selection Sort

However, selection sort runs quite speedily on smaller lists, often returning results faster than divide-and-conquer sorts such as quicksort and mergesort, simply because on shorter lists. Often when a divide and conquer sort has partitioned a large list or array into smaller sizes, the divide-and-conquer algorithm will then run simultaneous selection sorts to put the list or array in order faster.

Another substantial reason to use selection sort is that it uses very little memory and is known for being CPU-light. If the coder is working in a space where memory is limited or costly, this feature can be a tremendous advantage. For example, when using Flash memory, every write function shortens the life of the memory. The option of selection sort should be considered in situations such as these, because selection sort does not require an additional file to be built to house data. All action takes place within the algorithm and memory.

In comparison with other algorithms, selection sort almost always performs more quickly than bubble sort or gnome sort.  Join an interesting conversation here.

Comparison: Selection Sort Versus Insert Sort

However, insert sort almost always is faster and more efficient. To understand why, a coder must understand the concept behind insert sort.

Like select sort, insert sort uses two loops to place a list or array in order. However, the way in which the list is sorted differs.

With select sort, the algorithm must loop through each item in the original list in order to find the lowest value. However, with insert sort, the algorithm takes a value from the original list and inserts it into the proper place on the sorted list. This makes for a much faster algorithm. An example of an unsorted list is below, to help explain the differences between select sort and insert sort.

Unsorted List
5
65
12
15
98
3

An insert sort algorithm would take the first entry on the list (“5” in this case) and place it as the first entry in the sorted list. Meanwhile, a select sort algorithm would go through the entire list and then select the lowest number (“3” in this case). That number would then be placed as the first entry on the sorted list.

The insert sort would then take the next number (“65”) and place it after the number 5 on the sorted list. The select sort algorithm, though, would need to go through the entire list again, take the number “5” and then place it as the second entry on the list. As can be seen by the example, insert sort generally takes less time than select sort, because it is more efficient.

Also, classic insert sort is considered a stable sort, meaning that the original order of the list is respected when it does not interfere with the sort. For example, if insert sort were tasked with organizing the following sample list by the first integer (12, 34, 5, 9.6, 9.5), the list element “9.6” would appear before the list element “9.5” in a stable sort result.

This result differs from select sort, which is considered an unstable sort. If the same list were processed by the select sort algorithm, the results would either be (5, 9.5, 9.6, 12, 34) or (5, 9.6, 9.5, 12, 34). There are two possible results, as the original order of the list is not respected.

Selection Sort: Easy to Learn for the Neophyte Programmer

Selection sort is one of the simplest algorithms, which means it’s easy for the beginning coder to implement. The basic nature of the algorithm ensures its continued use as well, meaning that most coders are familiar with selection sort and will understand the coder’s usage of the algorithm in a program. This near universal familiarity means that selection sort can be used on projects with multiple coders, as it is so basic that nearly every member of the programming team can assume to be familiar with it.

Even if a team member has not encountered selection sort before, the functioning behind the algorithm is easy to comprehend and shouldn’t confuse an individual who is unfamiliar with it. Again, this is an advantage for selection sort, which is easier to understand for most people than other sorting algorithms.

Why it’s Valuable to Know Selection Sort

Although selection sort may not be appropriate for every array or list that needs sorting, it should be considered for small lists, especially if the coder is working under tight memory restrictions. In some instances, selection sort is even faster than divide-and-conquer algorithms such as quicksort. No matter what type of sorting the coder generally encounters, selection sort should be an algorithm that the coder is familiar with.

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Scanner Java: What is Scanner Class In Java?

coding scanner java

On the surface, the question what is a scanner class in Java seems easy. A scanner class is a class in Java that allows the program to see user input. However, for the beginning programmer, this information may not be enough. Therefore, this article will examine the subject in depth.

What is Java: An Introduction to the Language

While Java has been around for a while, some history may be in order to understand exactly what a scanner class in Java entails.  After all, without an understanding of the language, the coder may not realize how crucial the scanner class is to Java programming, and may completely overlook the class's utility.

Java was originally developed by James Gosling in 1991 for use in one of his projects. Interestingly, the language was originally known as “Oak” due to a tree that lived outside of Gosling's office.

After going through iterations such as “woods”, the name “Java” was chosen at random from a list of words. The name “Java” was not planned in the slightest.  Tutorialspoint offers an interesting history of Java.

Incidentally, the JavaScript programming language only shares certain features with Java. The two programming languages are not related and confusion between the two can be costly. Code written in Java will not run in a JavaScript environment and vice-versa.

Ultimately, the Java programming language was released in 1995 by Sun Microsystems and became extremely popular for a number of reasons.

First of all, Java is platform independent, meaning that the Java Virtual Machine interprets the code on which ever machine it runs on. Java does not need a separately compiled version of a program for each computer it needs to run on to function properly.

The error checking is also robust, unlike some other popular languages, and Java also supports multi-threading, which almost all modern computers can use to speed processing.

Also, Java is mostly open-source, with much of the source code being released to the general public by Sun in 2006. So, any proficient coder can look at the source code and optimize it or alter it.

Certain other languages, on the other hand, may only be altered by their respective owners, slowing down innovation and creating bottlenecks.

However, possibly the most salient reason for Java's success is that it implements object-oriented programming, which is an increasingly popular category of language among coders and is crucial to understanding the concept of a scanner class in Java.


Why and How Java Uses Classes

As noted above, Java is an object-oriented language. This means that snippets of code are given attributes and treated as objects would be in the physical world.

For example, in the real world, a bicycle may have two wheels, be red and have a horn. In the coding world, these attributes would be represented by classes.

As is always the case with a programming language, objects and classes have a specific naming convention which must be followed.

Generally, in Java, the naming convention is object.class. Please note that other programming languages also follow this convention, most notably JavaScript.

But why do programming languages bother with this? The computer doesn't care about objects or classes, so why would a language bother with being object-based? 

Well, the computer may not care, but humans are intrinsic tool-users, so we are used to dealing with objects every day. So, object-oriented programming is an attempt to make programming more natural for humans.

Although object-oriented programming may not seem natural for most people, compared to languages like FORTRAN or COBOL, object-oriented languages are easier to learn.

So now the coder understands a major reason as to Java came to become one of the most popular languages in the world.

The coder should also understand what a class is, and how objects in Java use object-oriented programming in order to make coding concepts easier for coders.


The Scanner Class in Java: A Special Case

However, the scanner class is particular to Java, and the concept should be fully explained. The scanner class is part of the Java util package, which is also important to understand.

The Java util package contains a number of classes that are crucial to effectively working with Java. As always, the naming convention is object.package.class. So when using the util package, the proper nomenclature would be object.util.class. 

While this article is concerned with remaining simple, coders who wish to find a more complex definition of scanner class in Java would be advised to visit geeksforgeeks.org

The first, and perhaps most important class is “arrays”. This class allows the Java user to search and sort arrays.

Arrays are often used in programming languages—they essentially are lists of variables that store information, including letters, numbers and even other arrays. Being able to search and sort through arrays is crucial, and this util class allows coders to do just that.

There are many other util classes which are important to all levels of coding. 

They include the Dictionary class, which helps map keyboard presses to values, the EventListenerProxy which can aid in getting input from users, and the EventObject class, which helps the coder make something happen onscreen when something else occurs.

However, almost unarguably, the most important class contained in the util package is the scanner class. The scanner class is a simple text parser that allows a program written in Java to “see” primitive types and strings.

In other words, this class allows an object to react to what a user types after the user inputs a string.

This class offers the easiest way for a beginning programmer to add interactivity to their coding.

It is often used, even when there are other alternatives available, due to its utility. However, there are some situations in which another class may be more appropriate.

For example, the scanner class should be avoided when creating an application needing fast input response, such as a game. The class has a slow response time and therefore gaming would not be appropriate.

However, for most other uses, the scanner class excels. General text input is handled very well by this class, and so text input for databases, spreadsheets and other programs is often given to this class in Java.

It's difficult to envision the Java environment being as easy-to-use and successful as it is without the usage of scanner class.


A Sample of Methods for the Scanner Class in Java

Of course, like almost any class, the Scanner class has methods which help define what the scanner is doing at that particular moment. A few of those methods are as follows:

The method listed as close() voids the scanner completely. This method stops whatever the scanner is doing and closes it. This method is obviously useful when the coder wishes for the scanner to completely cease functioning.

Meanwhile, the method listed as FindInLine() is used to find the next sequence constructed from the specified string, ignoring delimiters.

The final example is hasNextBoolean() which looks to see if the text response is a yes or no answer and then respond accordingly. As with all Boolean functions, only yes or no answers are accepted with this method, which is useful in certain situations.

If the reader is interested in a more comprehensive list of methods for the scanner class in Java, Javatpoint has an extensive list, and is highly recommended.


Effectively Using The Scanner Class In Java

As can be seen from the above examples, the scanner class is flexible and useful. However, like most programming tools, there are situations in which the use should be avoided.

For example, if the coder is attempting to create a multithreaded program, choosing to use the Java Scanner class should be avoided unless external synchronization is used. 

However, this is no reason to avoid the scanner class in Java. While exceptions do exist, this class is one of the most used in all of Java, and with good reason.

When a coder needs a simple, reliable class for receiving text input from a user, the scanner class should be considered. The prepared coder should be familiar with the scanner class and use it today.

Featured Image via Freepik

What Is The JavaScript ParseInt Function?

computer screen showing javascript code

JavaScript is a powerful programming language that thrives on the web. It comes with a number of functions that make programming websites and web application simple. A useful function Javascript provides is the parseInt() function.

The JavaScript parseInt() function parses a string and returns an integer value. This function is useful for times where you want to convert data a user has inputted as a string to an integer. The applications for parseInt() are numerous, and it will become a valuable tool in your programming toolset.

We will walk you through how the parseInt() function works, practical applications of the function, technical information, and some common mistakes programmers make when using the parseInt() function.

How To Use The JavaScript ParseInt() Function

In order to explain what the parseInt() function is, and how it works, we will break up the information into the following sections:

  • Overview
  • Constructor
  • Use
  • Examples
  • Return values

Overview

The parseInt() function parses a string and either returns a number, or NaN(Not a number) if the string read in does not contain a valid number. In a perfect world, you would only deal with solid numbers that can easily be converted into integers, like 10, or 500.

However, you may find times where there are numbers that you want to convert to a string that are represented as hexadecimal numbers. Hexadecimals aren’t the only numbers you have to concern yourself with, there are also octals and other number bases that you may need to convert.

Thankfully, the parseInt() function is versatile and accepts parameters that specifically help programmers convert strings to numbers based on radix. This is important work done by the constructor of the parseInt() function.

Constructor

The parseInt() function takes the following parameters:

  • String
  • Radix

The String you want to parse is a required parameter in this function.

The radix parameter is an optional parameter that specifies what numeral system needs to be used for the conversion process. If you were to input a radix of 16, the parseInt() function would interpret the number you are parsing from the string as a hexadecimal.

The radix parameter can be any value in between 2 and 36. Because the radix parameter can be omitted, it is important to know what default value is used. When there is no radix parameter defined there are a few assumptions JavaScript makes to interpret the string.

If the string begins with “0x” then the radix interpretation will be 16. Otherwise, any other value provided to the parseInt() function will be interpreted with the radix of 10. It is important to know this going into using the parseInt() function in case you run into miscalculations of integers you want to parse.

When you start using the parseInt() function, it is important that you get in the habit of defining your radix. This is especially true if you are working with large data sets that have the possibility to deviate. Creating a function that shifts the radix based on expected number value in a string is well worth your time.

Use

Because JavaScript parseInt() is a function, you usually want to set it to a variable. This way you can store the integer value returned by the function. Common usage of the parseInt() function is as follows: var a = parseInt(“10”);

Examples

The parseInt() function can convert many different string values to integers. Regular numbers, octals, and hexadecimals are among some of the most common conversions used with the parseInt() function. The following examples are common uses of parseInt():

  • parseInt(“10”) returns 10
  • parseInt(“010”) returns 10
  • parseInt(“17”, 8) returns 15
  • parseInt(“C”, 16) returns 12
  • parseInt(“-0XC”, 16) returns -12

Notice that if you define the radix value as 16, you can use characters that are not numerals without throwing a NaN error.

Return Values

When the parseInt() function is used correctly it returns an integer. However, there will be times when the parseInt() function cannot correctly parse a string, in those cases, it will return a NaN error.

It is important that you pay attention to the return value provided to you by parseInt() and create an exception that handles the NaN error.

If the first character in the string cannot be converted to a number, then the Javascript parseInt() function will throw a NaN error. Likewise, if you supply an empty string, the parseInt() function will return nothing.

Applications Of Javascript ParseInt Function

The parseInt() function is a powerful tool that has a number of practical applications. The following applications of the parseInt() function demonstrate its practicality:

  • Sanitize user inputs
  • Convert octal and hexadecimal values
  • Format Microsoft JSON Date

Sanitize User Inputs

The primary application of parseInt() is to sanitize user inputs. There may be moments where you have users input text into a text box. Any time the user inputs text into a text box, that value will be referred to as a string.

In order to pull the integer value you desire from the string, you must use the JavaScript parseInt() function. Getting comfortable with this function will better prepare you to deal with a common interaction paradigm on the web.

Convert Octal And Hexadecimal Values

Javascript’s parseInt() function isn’t just useful for sanitizing user inputs, it is also useful as a conversion tool. There may be times where you are given hexadecimal or octal values as strings. No one wants to have to look up a key every time they see one of these values.

Unless you have octal or hexadecimal values memorized, or you understand the conversion, the parseInt() function can do much of the heavy lifting in converting those values into human readable integers. You might be creating a website component that relies on strictly integer values. The best way to interpret those values would be to use the parseInt() function.

Format Microsoft JSON Date

Another key practical application of parseInt() is for use as a date converter. There will be times where you have to format Date information to make more human-readable text. In a popular example on StackOverflow with over 674,333 views a user explains how to use the parseInt() function to sanitize date data.

Notice that in most examples parseInt() is used to make information more readable. Practical applications of the parseInt() function generally make the use of other functions easier. Knowledge of regular expressions will help you better use of this function.

Technical Information

an open book about javascript programming

Image Source: Unsplash.com

 

The JavaScript parseInt() function is usable on all modern web browsers. Basic support is available for all web browser platforms, and each browser supports parsing leading zero strings.

This function also has 3 specifications that can easily be read for more technical information on the parseInt() function. The following specifications exist for parseInt():

  • ECMAScript 1st Edition
  • ECMAScript 5.1
  • ECMAScript 2015
  • ECMAScript Latest Draft

Another technical case that is important to understand is how different versions of ECMAScript numeric strings with leading zeroes that do not have defined radixes. ECMAScript3 discourages the use of parsing octals with no radix defined. In ECMAScript 5, parsing an octal without defining the radix as 8 will definitely not work. It is important that you always define your radix when using the parseInt() function on octal and hexadecimal values.

Common Mistakes

One of the most common mistakes programmers make when using JavaScript parseInt() , is not setting their radix. A user may parse a string that has a leading zero and receive output that is different from what they are expecting. This Stack Overflow statistic demonstrates that this is a common error with over 14,880 views over 7 years.

To solve this mistake, it is imperative that you understand how parseInt() parses strings when no radix is supplied. Always supply a radix, it is better to be explicit when using the parseInt() function.

The ParseInt() Function Is A Necessary JavaScript Tool

Javascript’s parseInt() function can be used in a number of instances to make JavaScript development easier. Common uses of this function involve parsing strings to convert numbers into an Integer format that can easily be manipulated.

It is important that you remember to define the radix. If you don’t define your radix you could run into issues using the parseInt() function that can slow down your development time. As always, consult StackOverflow or Quora if you run into bugs that you cannot fix on your own!

 

Featured Image Source: Pixabay.com

Simple Guide to Understanding a Bootstrap Grid System

coding using bootstrap grid

Before you can dive too deeply into a technology or development tool, you should have at least a high-level understanding of what the product is – or is not.

Bootstrap is a technology tool created as a front-end framework for developing web pages and applications. It has become one of the most popular tools referenced on the GitHub website, garnering in excess of 100,000 stars from users of Bootstrap functionality.

Some of the factors contributing to the success of Bootstrap are:

  • Price (it’s free to download)
  • Platform – Bootstrap is open source
  • Flexibility – it contains HTML and CSS templates for quickly designing buttons, forms, and other website content
  • Optional JavaScript extensions available
  • Broad acceptance and utilization by website and web application developers
  • Continuous additions to functionality and responsiveness to the developer community

With such a growing user base and many developer contributors to the product, it’s no wonder Bootstrap has experienced an amazing level of adoption for designing web applications and websites.

Functionality and Simplicity Combined

coding with red keyboard

Image via Pxhere

Bootstrap today serves as a full-featured development and web page design tool for developers of all skill levels.

By combining architectural features to support advancements in such in-demand technologies as Saas, JavaScript, and CSS with ease of use, Bootstrap has become one of the most recognized and popular frameworks for front-end website building.

The flexibility of Bootstrap lets you as a developer select the features and components that most suit the design of your web pages. Variables can be utilized for such functions as controlling padding, color, and settings of individual objects.

Bootstrap’s responsive design and grid-based functionality enable you to create multiple variations of web pages for use on low or high-resolution devices, whether developing for mobile devices, tablets, laptops, or PCs.

With its focus on a grid design, Bootstrap is a relatively easy tool to gain proficiency in, building full websites that adapt to the devices running your applications.

A Simple Guide to Understanding

the Bootstrap Grid System

The Grid Concept

Bootstrap builds your webpages utilizing a grid layout that you can utilize to format responsive web pages for multiple devices. The responsive attribute refers to the application recognizing the device in use, and resizing images appropriately.

In general, the Bootstrap grid is designed to facilitate a width of 12 columns, although you can group columns together creating fewer but wider columns, if your design does not call for all 12.

If you use more than 12 columns in your grid, Bootstrap will stack them. In addition, where a large display may accommodate 12 columns quite readily, small screens will provide better presentation when columns are stacked.

 

Options for Grid Classes

Bootstrap offers you multiple options in creating dynamic and responsive screen layouts:

  • Xl – for screens equal or greater than 1200px
  • Lg – for desktops and laptops with screens equal or greater than 992px width
  • Md – for smaller laptops with screen width equal or greater than 768px
  • Sm – stepping down to tablet-size screens equal or greater than 576px wide
  • Xs – sized for mobile devices such as phones, with screens less than 576px wide

Grid classes can be mixed to provide more flexibility in layout. Each class will also scale to the next larger class, so if you want to design a grid for small and medium display, you can simply specify small.

Basic Rules for Using Bootstrap Grids

There are a few specific rules to keep in mind when building grids with Bootstrap:

  • To assure the desired alignment and padding of rows, the rows must be placed in a .container-fluid (for full-width) or .container (fixed-width)
  • Your content must always be placed in columns
  • Columns must be the immediate children of rows
  • Rows can only be used to contain columns
  • If you attempt to provide over 12 columns on a grid, they will be stacked
  • Column widths are specified in percentages of total width, and are fluid, making them sized in relation to their parent elements
  • All rows should be placed in a container

Bootstrap provides predefined classes for quick generation of grids, such as .col-sm-4 and .row

How the Grid Works

coding with laptop

Image by Pixabay

Bootstrap’s grid is designed for responsive layout, utilizing the familiar concept of rows and columns.

Containers

Groupings of these rows and columns are placed in at least one container, but possibly more. In its simplest form, a grid can consist of a single container, with one row and column:

<div class=”container“>
<div class=”row“>
<div class=”col“>Here is the grid content!</div>
</div>
</div>

This example, of course, does not utilize the classes such as Flexbox, CSS, or JavaScript components.

The container is a key element of Bootstrap. It essentially controls the width of your layout and is the root of your grid. The container can contain any element of your layout – rows, columns, and other markup content.

You can include multiple containers on a page to suit your design preferences, and a container may contain multiple rows.

Proper use of containers will ensure optimal alignment on the page, due to the property of container padding that keeps rows aligned with 15px margins. Inserting rows without being included in a container will result in a horizontal scroll that you did not intend, and your viewers will not appreciate.

Inserting Your Content – Columns

Formatting your content is never done in the rows of the grid. Content is placed in columns, and columns are placed in the rows.

With Flexbox implementation in Bootstrap 4, both vertical and horizontal alignment are accomplished with Auto-margin and Flex Utility classes.

Columns are invaluable in your layout design for multiple reasons:

  • Columns can vary in width automatically for responsive design
  • Columns create the horizontal placement and division across the display
  • Can contain other rows and columns through nesting
  • Will always be the same height as other siblings in the row
  • Columns create the horizontal separation across the display or viewport

Space generated between columns are referred to as the gutter.

Columns in a row will be spread horizontally across the row. When you include over the base 12 columns of the grid, the remaining columns will be stacked or wrapped vertically down, referred to as “column wrapping.” This may or may not be the effect you desire for your web page.

Flexbox introduces a new term for columns – Auto-layout columns. Flexbox offers additional controls over the alignment and justification of columns for your page layout.

 

Mobile Comes First

As part of this simple guide to understanding the Bootstrap grid system, you should also be aware that Bootstrap inherently puts mobile presentation first. This makes perfect sense, as you take a look around to see how website users are accessing your web pages – on phones and tablets.

With a “mobile first” approach to responsive design, xs (the smallest px value) is the default breakpoint in building your grid. Keep in mind that higher breakpoints will override smaller values. Size your columns accordingly, perhaps defining 3 columns for sm, but 4 columns when designing for md or higher values.

Grid Design Considerations

 

When designing your grid layout, keep these concepts in mind:

On smaller screen widths, columns will stack vertically and maintain their full width, unless you incorporate a specific class within your HTML markup details. Using such a specification will eliminate the possibility of stacking that you did not intend.

Smaller classes specified on your grid also apply to larger screens, so you truly only need to specify the smallest device/display you intend to support on your web pages.

Your columns will be equal height in the same row. Multiple options can be used to control formatting details, including Flexbox justify and alignment functions, auto-margins, and vertical centering.

Browser Support

Utilizing a design tool like Bootstrap would be all but useless if your browser did not support the results of your design. This is certainly not an issue with Bootstrap. Your web pages will be supported by nearly every popular browser that hits your website:

Browser Support

Mac

Chrome, Firefox, Opera, Safari

Windows

Chrome, Firefox, Internet Explorer (10+), Microsoft Edge, Opera

Mobile Devices

Android

Chrome, Firefox, Android Browser and WebView, Microsoft Edge

iOS

Chrome, Firefox, Safari, Microsoft Edge

A Brief History of Bootstrap

Initially developed by Jacob Thornton and Mark Otto as a framework to facilitate development for internal use at Twitter, Bootstrap (originally named Twitter Blueprint) grew from a tool to promote consistency in interface design into a full-function tool that was released in 2011 as an open source product for website developers.

Bootstrap 4 was released in January 2018, with an enhanced toolkit for developers that now supports the current migration to CSS flexbox and Sass.

Jacob, Mark, and a handful of developers continue to enhance and add functionality to Bootstrap, demonstrating their commitment to the on-going value of the product for current and prospective web developers.

 

Featured Image via Pxhere

 

What Is the Getline C++ Function?

learning the getline c++ function

C++ is one of the most popular programming languages being used for application development today and has earned its popularity over a period of over 20 years (originally created circa 1979), with an initial standardized version released in 1998.

C++ offers developers many benefits:

  • Object-oriented architecture – having such attributes as inheritance and polymorphism
  • Platform agnostic – run your compiled C++ applications on anything from a desktop computer to a smartphone
  • Low-level language – you work closely with platform characteristics such as memory management and device management
  • Fast, efficient performance – C++ is a compiled language, as opposed to interpretive alternatives, providing performance similar to C applications, and generally out-performing C# programs
  • Great for applications such as networking, creating operating systems, server-based functions, device drivers, and gaming

With an estimated population of C++ developers over 1.5 million strong worldwide, there are many sites, forums, and user groups available for training, tips, and collaboration.

 

C++ Getline Function – the Basics

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Image via unsplash.com

 

When reading a data stream from any input source such as the keyboard or a data file, you have options for how you retrieve and manage that process. You can utilize the standard C++ cin function, or you may choose to use an alternative – the getline function.

What is the C++ getline function, and how does it work?

The getline function in C++ serves to extract characters or a stream of characters from a specified input stream, appending the stream to the string receiving the data until either a specified delimiter or new line is detected, or end of file is encountered.

Getline is a standard C++ library function and offers multiple format/syntax variations:

Format 1:

istream& getline (istream& is, string& str, char delim);

Parameters in this format are:

  • is – an object in the istream class that provides information about the source to be read for input for the getline function
  • str – the receiving string object where data is to be stored after the function reads from the stream
  • delim – this parameter defines the delimiter character that tells the getline function to stop reading when it detects this character

Format 2:

istream& getline (istream& is, string& str);

This format is essentially the same as the first, with the exception that no delimiter character is provided. Getline function will recognize (‘n’) or new line character as the delimiter.

As an example using a delimiter character of “z”

istream& getline (istream& is, string& ‘z’);

In this example, if the ‘z’ character is found in the input stream, the extract will end, but the ‘z’ will not be included in the stream.

The basic function of getline is to extract data or characters from an input stream source, appending the information to the specified string object until new line or the specified delimiter is found. If the delimiter is detected, it is not passed to the string – it is discarded.

Note that the extract can stop for several reasons:

  • The delimiter is encountered
  • End of the source file stream is reached
  • An error condition is detected

If data is received as a result of the getline function, it replaces any characters previously stored in the string object.

Conditions and Errors Returned by the Getline C++ Function

 

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  • Eofbit – this indicates that the end of the source stream characters has been reached
  • Failbit – input data received by the function could not be properly interpreted as valid content of the type. In such instances, the internal data and parameters that existed before the call are preserved.
  • Badbit – an error condition other than eofbit or failbit has occurred.

Most developers are quite familiar with the “cin” standard C++ default input method, especially when dealing with streams such as keyboard input. The result can sometimes be troublesome since the cin function may result in error conditions when it receives input content that it cannot process, resulting in a fail state from the function.

Until the fail condition can be corrected or cleared, the unprocessed information will remain on the input stream. To continue, either the input must be corrected for the function to proceed, or the fail state must be cleared and handled by your program.

Getline Is a Better Solution for Extracting Input

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Image via unsplash.com

 

Getline is a more robust and error-tolerant method for reading an input stream for multiple reasons:

  • Both numbers and strings can be read without resulting in a fail state
  • When you want to read an entire file, getline can be easily embedded to read input through the file within a loop, extracting all content efficiently, and cleanly exiting the loop when end of file isreached.
  • Getline is custom-made for processing through a delimited file since you’re able to provide the delimiter character to be recognized as your stop point.

Special Considerations Where the Getline C++ Function Shines

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There are certain conditions where getline is your best choice for accepting a string from keyed input or when reading data from a file.

Blank Lines in Input Stream

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Blank lines in an input stream can create a problem for your program since getline will interpret the newline character at the end of a blank line, sending the blank content to the output string.

Fortunately, by testing the length of the string, it becomes very easy to omit the blank entries, looping through the input stream for the next valid line, as in this code example:

while (str.length()==0 )

getline(cin, str);

This is an easy method of skipping stream content lines where the length of the string is 0 (bypassing blank lines).

 

Converting String Content

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Using the string parameter in a getline function provides ease of applying the C++ converter functions to transform string-to-long-integer (stol), string-to-integer (stoi), string-to-double (stod), and string-to-float (stof) formats. Since the data has already been read into a string object, it is easily converted as needed by your application.

Coding and Use of the Getline C++ Function

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There are some additional coding considerations that illustrate best practices or cautions against inefficient code:

When executing a getline function, memory will be allocated for the string to contain data from the input stream. If the function fails or otherwise encounters an error condition, the memory may not be freed for other use. In such cases, you should free the allocated memory. A good practice is simply to always free the allocated resource when finished with the function and data string.

Never just assume that your code worked flawlessly. C++ and its functions provide many options for discovering and identifying error conditions. Checking your status conditions when functions are executed will ensure that the expected results are realized and will also inform you of any data or program exceptions that need to be addressed.

Another best practice is to not mix types of input coding, such as using cin and getline in the same process flow. The reason – cin is well-known for encountering issues with input, mainly due to its lack of type tracking. This could result in a subsequent getline receiving empty results. It’s much more consistent and reliable to utilize the getline C++ function to provide better control of the data stream, error checking, and data manipulation.

Before processing data extracted from the stream, always check for errors returned by getline() (just as you should for any other input/output (IO) operation utilizingstreams).

If your getline() function (or any IO operation on a stream) has set the associated failbit or badbit, do not process the data. You should not assume the data returned is valid or usable for processing. The eofbit is not required to be checked in the loop since this is a normal return and does not necessarily indicate an error that should prevent processing of the data received.

Learning More

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Image via unsplash.com

 

With so many types of data and files that you encounter in writing applications, there are many different ways to manage data streams and strings. You can gain a great deal of additional information on the best ways to utilize the getline C++ function, including:

Investigating each of these resources for insight regarding what the getline C++ function is and how to use it in the development of your application, will prove valuable in developing your C++ skills.

What Is A Blink HTML Tag?

programmer using the blink html tag

Hypertext Markup Language (HTML) is one the cornerstones of building web applications and web pages and has been for decades.

Along with Cascading Style Sheets (CSS) and JavaScript, HTML forms the basis for the most popular technologies for creating sites on the world wide web.

First released in 1993 and with its latest release being HTML5, web page constructs that utilize HTML elements can be easily understood and transformed into interactive web pages by a variety of browsers.

HTML offers web page developers a set of building blocks that generate structured pages, handling images, headings, lists, links, and other elements consistently and efficiently.

Information provided to a web browser through HTML, CSS, and scripts such as those provided through JavaScript code generate the appearance and functionality experienced by viewers of the associated websites.

HTML “tags” provide information to the browser that defines the type of data or function to be applied to the associated elements of the web page. Examples are:

  • <body> provides a definition of the document’s body
  • <button> defines a button that is clickable to the browser
  • <header> defines the section or document header
  • <img> provides image definition
  • <meta> defines the metadata for the HTML document

Standards are maintained and set for CSS and HTML by the World Wide Web Consortium (W3C). These standards, though not binding and mandatory, are strong recommendations by the technical community that forms the W3C to adhere to best practices and guidelines for consistency in web design and development.

Most popular web browsers tend to adhere to the standards published by W3C to promote compatibility and a more universal set of coding practices.

What Is a Blink HTML Tag and How Does It Work?

One HTML tag that may not be as well-known or frequently used is the <blink> HTML tag. Blink is a non-standard tag that can be utilized to create enclosed text that blinks – or flashes – slowly.

Most web page developers have avoided the use of this tag, mainly due to the reaction of web page visitors who deemed the effect annoying, with text turning off and on. The blink effect makes the text image alternate between being visible and invisible.

Few modern web browsers still support the blink HTML tag, and some – such as Internet Explorer – never supported the blink HTML tag at all.

Blink HTML tag syntax includes an open and close pair of tags:  <blink> and </blink>
respectively.

In practice, different browsers will handle the blink html tag differently (if they recognize it at all). For example, the Firefox browser interprets the blink tag to make the associated text invisible for ¼ second,then visible for ¾ second, alternating between the two effects.

Alternatives to the Blink HTML Tag

The blink HTML tag was always seen as a non-standard tag that few browsers supported, and most that supported the element in the past have since dropped support of the tag. Even the Opera browser, which once did support the blink tag, ended support of that attribute long ago, with version 15 of the browser.

But even if the blink HTML tag is largely unsupported and will not be recognized by most browsers, there are other ways to accomplish a similar effect.

CSS Code There is a method through CSS to provide a blinking effect. Using the CSS animation properties along with definition utilizing the @keyframes rule, you can generate blinking text. Try this sample code from ComputerHope.com to create a blink class and put it into use.

<style type "text/css">

<!--
/* @group Blink */

.blink {

-webkit-animation:
blink .75s linear infinite;

-moz-animation:
blink .75s linear infinite;

-ms-animation:
blink .75s linear infinite;

-o-animation:
blink .75s linear infinite;

animation: blink .75s linear infinite;

}

@-webkit-keyframes blink {

0% { opacity: 1; }

50% { opacity: 1; }

50.01% { opacity: 0; }

100% { opacity: 0; }

}

@-moz-keyframes blink {

0% { opacity: 1; }

50% { opacity: 1; }

50.01% { opacity: 0; }

100% { opacity: 0; }

}

@-ms-keyframes blink {

0% { opacity: 1; }

50% { opacity: 1; }

50.01% { opacity: 0; }

100% { opacity: 0; }

}

@-o-keyframes blink {

0% { opacity: 1; }

50% { opacity: 1; }

50.01% { opacity: 0; }

100% { opacity: 0; }

}

@keyframes blink {

0% { opacity: 1; }

50% { opacity: 1; }

50.01% { opacity: 0; }

100% { opacity: 0; }

}

/* @end */

-->

</style>

Once you create the above code, you’re ready to apply the class to the text of your choice, such as:

<p class="tab blink">Here is some blinking text.</p>

Modifying the code examples to utilize different values will allow you to “tweak” the code until you get the results you want to present to the viewer.

Microsoft also created a proprietary blink HTML tag to be used with their Internet Explorer browser. The tag was never adopted as part of the HTML, but subsequently dropped it altogether, and it is no longer supported even by Internet Explorer.

CSS at one time could provide the effect through the “text-decoration: blink” specification, but this too is a non-standard method of producing blinking text, and is not a working solution for most browsers today.

JavaScript JavaScript provides a more functional and supported method
for presenting blinking text on your web page:

var blink_speed = 500; var t = setInterval(function () { var ele = document.getElementById('blinker'); ele.style.visibility = (ele.style.visibility == 'hidden' ? '' : 'hidden'); }, blink_speed);

Keep in mind that if you’re thinking about including blinking text on your web page, you should probably reconsider, with the many concerns and cautions against using such an effect on your web pages.

Why Blink Is a Bad Idea

There are many reasons or opinions that back up the recommendation that blinking on a web page is not only a bad idea or distracting for website visitors but is strongly opposed by organizations and standards institutions.

W3C’s own Web Content Accessibility Guidelines (WCAG) provide a great deal of information related to why “blink” is not a good practice. Some of the key reasons to avoid the use of blinking text are:

  • W3C agrees with the general consensus that blinking text is annoying and detracts from the overall appearance of a web page.
  • Even the “creator” of the blink concept (most often credited to Lou Montulli, a Netscape engineer) opines that his creation was likely the “most hated of all HTML tags”.
  • Apple advised developers to avoid the practice as far back as 1982, with their suggested guidance that “flashing text should only be used to indicate imminent destruction of data or the program”.
  • From a practical viewpoint, there is documented evidence of the negative impact blinking video segments can have on individuals who have certain disabilities. In fact, the W3C Web Content Accessibility Guidelines (WCAG) go into great detail regarding standards for “flashing” content on web pages, highlighting the detrimental effect it presents to individuals with certain disabilities or those who are subject to seizures triggered by visual stimulation
  • Specifically, the standard calls for thecapability for web users to stop or hide the effect:

“Moving, blinking, scrolling - For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential”

Although the standard admits there could be overlap in the definition of blinking vs. flashing, adoption or use of all such negative effects is to be avoided in nearly all cases.

Utilizing a Blink HTML Tag

Although the blink HTML tag is officially in a non-supported status for all popular browsers, you can still utilize the effect through other means (JavaScript or CSS methods). Still, the technique or any use of blinking text is not advised as a good practice.

Most developers or website visitors consider a blink HTML tag or blinking text on a web page through any means to be:

  • Distracting
  • Annoying
  • Potentially unhealthy

There are many HTML tags and CSS decorations or animations that are much more attractive and appropriate for your web pages. Consider the use of other techniques over blinking or flashing presentations.

Keywords: blink html

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The Top 21 Most Common Java Interview Questions

a row of young people sitting by the wall while waiting for the turn to be interviewed

It pays to know of the one most popular programming languages.

In 2016, Oracle noted Java was used by approximately 9 million developers and running on 7 billion devices worldwide. That’s an exponential growth curve, considering it’s only been public for less than 25 years.

Java was born in Santa Clara, California as part of the Silicon Valley boom in the early 1990s. Java was developed at Sun Microsystems to boost the abilities and effectiveness of C++ language.

It was released to the public in 1995 and quickly gained popularity. Java was designed to run independent of platform. Any device that has Java Runtime Environment (JRE), a lightweight application, can run a Java program. This provided developers a “write once, run anywhere” programming language. It significantly reduced the coding and resources necessary to write a program for multiple platforms.

Java was eventually acquired by Oracle as part of its larger purchase of Sun in January 2010.

Of all the programming languages available, how did Java surpass them and become such a hot commodity in today’s job market?

Why Java is One of the Top Programming Languages

Java is undeniably popular. It consistently leads the TIOBE index – a measure of the popularity of programming languages created by the TIOBE Company in the Netherlands – with the most recent rating of 17.8%. That’s up 5.4% from last year.

Below are just a few of the reasons why Java has become so popular:

  • The Five Principles: Sun Microsystems wanted to build on the C++ language and create something that more people could use. They explained this goal as Five Principles which guided the initial design and subsequent iterations of the language.
  • Open Source: Anyone can create Java applications at no cost. A massive community of users has grown around Java, providing additional resources and expertise for developers. Message boards and forums provide free publicity and ongoing training for users. With a growing library of functions and classes, Java is an easy choice when looking to deliver results quickly.
  • Concurrent: Programmers can process data in parallel, meaning multiple programs can run at the same time.This increases the efficiency and power of programs written in Java.
  • Wide Range of Uses: Java is used in banking and financial services, IT, and stock market trades. It provides a solid foundation for websites. Java is critical for applications in a wide range of industries.
  • Big-Name Users: Companies and programs that use Java include Minecraft, Adobe Creative, Google, and more.

Thanks to the high demand for this skill set, average salary range has been reported at $93,570 for a Java programmer. It’s no wonder Java developers and programmers are in such demand.

Knowing Java is only part of what you need to earn a position with one of the top companies in the world. Let’s look closely at the interview process and the questions you can expect.

Interview Questions

The interview is designed to give the business a better understanding of who you will be as an employee and how you will work as part of a team. The questions will also cover specific technical skills you’ll need.

Problem-Solving Questions

Managers want problem solvers in every layer of employment – from entry level to top management. The hiring manager will test your personal skills by asking about missed deadlines, office conflicts, loss of data, and overlapping deadlines. They are not only looking to see that you know how to fix a problem but want to know how you can deliver solutions when problems occur.

Below are a few of the questions you should prepare to answer:

question mark
  • What is a challenge you’ve faced in the past and how did you handle it?
  • Have you ever had a project that was behind schedule? How did you manage the work and meet the deadline?
  • Tell me about a time where you faced a problem you couldn’t solve. How did you handle it?
  • Describe a creative solution you used to handle a work-related problem?
  • What kind of troubleshooting process do you use in your work?

Leadership-Based Questions

Do you wait for a solution or do you lead by proactively finding the answer? Everyone has their comfort zone with leadership. Hiring managers want to know where you will fit within the company. They may ask questions about your proudest accomplishment, what do you want to gain from this job, or if would you speak up if you knew something in the process was wrong.

  • In your opinion, what makes a great leader?
  • What experience do you have that will help you in this position?
  • What work-related responsibilities have you had in the past?
  • If you knew a manager was wrong, how would you handle it?
  • What is your greatest strength and greatest weakness?

Java Interview Questions

Java is considered one of the easier programming languages, especially when compared to languages like C, C++, Fortran, and Pascal. Even so, there are core skills and expertise every developer and programmer working in Java should have mastered.

man having an interview

Source: Freepik.com

The technical questions in the interview will be designed to not only determine your comfort and competence in Java programming, but also check that you have the core skills for the position. Before the interview, make sure to review the job listing to identify what those skills are. Take time to brush up on those skills and have answers ready for any specific technical questions the interviewer might ask.

Let’s look at a few other common Java interview questions:

  • Can you explain what a “platform independent programming language” means, and why Java fits this description?
  • Can you explain the difference between StringBuffer and String?
  • Tell me what you know about the finalize() method?
  • Can you explain the difference in Set and List interface?
  • Why doesn’t Java support multiple inheritances?
  • Tell me what you know about Java Exception Handling? Is there a difference between “throw” and “throws”?
  • What is the Final keyword in Java? How is a super keyword used?
  • Can you explain the abstract class in Java? How is it different from an abstract class in C++?
  • How does static variable work in Java?
  • How does Java store objects in memory?
  • What are the differences between HashTable and HashMap in Java?

Keep in mind, these are common Java interview questions. Many jobs will require specialized technical knowledge and Java programming that isn’t covered by these questions. Understand the position you are interviewing for and the expectations for the job.

Next, we’ll go over a few other things you can do to ace your interview.

Appearances Mean Everything

Beyond knowing the answers to the top interview questions, landing the job is all about first impressions and professionalism. Employers are looking for Java programmers that fit within the corporate culture and take pride in themselves. Confidence in your abilities translates to confidence in your appearance and mannerisms.

man holding laptop

Below are some guidelines to acing the first impression:

Prepare for the Interview

You are an expert in your field, Java programming, but companies also expect you to know about them and how they are using Java. Go beyond the simple Google search and see what the company says about itself. Look at what others are saying about the company and who are their competitors. Review their business pain points and prepare responses on how you can solve them.

Dress Appropriately

Sometimes a recruiter or the hiring manager will provide guidelines on what to wear. If they don’t, do your research and learn what is expected in the corporate culture. Not every company will expect a suit, but some won’t give you a second glance if you wear jeans. In general, interviews tend to be more formal than your daily wear once you land the job.

  • Here are recommendations for women, including what to wear and suggestions on where to buy layers, blazers, dresses, and pants. You don’t have to buy the exact item in the article; use it as a guideline and tailor it to your style and budget.
  • Likewise, there are also suggestions for men for ties, shirts, and trousers. Again, make the style your own, but make sure it fits the expectations.

Print your Resume

Some companies and human resource departments still prefer paper. Print and bring a copy of your resume. It’s better to have it and not need it, then to not be prepared for someone to review your resume.

Accessories

Store your printed resume, laptop and any samples in a portfolio or briefcase, so they are crisp when you arrive. You will lose credibility if your work looks sloppy.

Follow Up

Gather business cards or contact information during the interview. Email a thank-you note within 24 hours (the sooner the better) of the interview. Express not only your thanks, but also your excitement and recap what you can bring to the company.

A Final Word on Java Interview Questions

Learning Java is only the first step in a career. Even as the demand for quality employees and the sheer number of companies using Java continues to rise, competition for jobs is still fierce.

Preparing for Java interview questions and doing your research before you meet with a recruiter is critical to landing the job you want. You may be the best Java programmer for a position, but if you can’t ace the interview and show what an asset you will be for the company, you may never get a chance to show what you can do.

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Everything You Need to Know About Arraylist Java

programming code on screen

Java programmers and developers are in demand.

With more than 7 billion devices using Java across the world, companies are looking for Java programmers. Even with more than 9 million Java developers, demand is high for new talent.

There is a good reason why Java is so popular with developers and businesses. Java eliminates many of the “quirks” and constructs that plague other languages. This makes it much easier to learn. Java is also an object-oriented language, supporting collaborating objects in a program. Java is distributed, so it supports network connectivity with TCP/IP support in Java class libraries. This lets an application written in Java open and access remote objects across the Internet.

One powerful feature of Java is the arraylist Java, or dynamic arrays that make it easier to input and use a collection of elements in Java. We’re going to take a closer look at arraylists in Java, an important feature in the language, and how they can be used.

Ready to go? Let’s get started…

A Little Background in Java

Java was built by a small group of engineers led by James Gosling at Sun Microsystems in 1992. The original goal of Java seemed simple – correct a few of the problems and inefficiencies in C and C++.

A core focus of the Java design was to have as few implementation dependencies as possible. This meant that Java code could run on all platforms that support Java without needing to be recompiled. Developers could write the code once and it could run independent of platform – or “write once, run anywhere” as it has since become known.

To keep Java programs portable, and able to run similarly on almost any combination of operating system or hardware, Java code is compiled into Java bytecode instead of an architecture -specific machine code. Java bytecode can then be executed by a Java virtual machine written for the host hardware and installed on the machine.

This ingenious design allows Java to be run on almost any machine or platform, saving programmers and developers time and effort when they are writing code for different platforms.

Where is Java Programming Used?

Over time, many businesses and programmers have taken advantage of the platform-independent power of Java.

Java is the basis for networked applications and a global standard for developing and creating embedded applications. It is the core of web content, games, and enterprise
applications.

Java is the foundation of apps in Android. The insurance industry, education groups, and healthcare organizations all use applications running on Java. Even government facilities and the department of defense rely on Java and Java applications.

Java programming is used in many different devices, including laptops and computers, smartphones, gaming consoles, medical devices, and navigation systems. Java is also a critical tool for websites. Java can be used to create programs, known as applets, that can be embedded in web pages. Applets create the interactive widgets and tools, like maps and games, found on many web pages.

Now that we have a little background into Java, let’s dig into what an arraylist Java is and how they are used.

What is Arraylist Java?

Java is an object-oriented program, which means data and information in a program can be manipulated and used just like a real-world object. Objects in data can be assigned classes, states, and behaviors which can be used to quickly group, sort, and organize information.

A Closer Look at Arrays

An array is one way to group and sort information. An array is known as a container object which stores a sequential list of elements of the same type. Another way to look at an array is as a data structure designed to hold a specific amount of data or information. The array is a collection of variables which are all the same type. Values or items within an array are known as an element.

When an array is created in Java, it is assigned a length which is fixed. No additional elements can be added to the array after it is created. Each element in the array is assigned a numerical index which can be used to quickly access the element.

The Difference Between Arrays and Arraylist Java

Like an array, an arraylist is used to store and manipulate elements. Elements in an arraylist are assigned an index to help in retrieval and manipulating the elements.

Unlike an array, and arraylist does not have a fixed length. It will grow and expand as new elements are added. Arraylists are also known as dynamic arrays. This means you don’t need to assign a length when creating an arraylist. Even when specifying an initial length for the data structure, an arraylist can add indices to accommodate additional objects or data as they are added.

With an arraylist, as elements are added the list expands. When an element is removed the list shrinks. An arraylist can accommodate any amount of data, objects, or elements.

There are a few key characteristics to keep in mind as you work with an arraylist:

  • Arraylists and null and duplicate values: An arraylist can accommodate null and duplicate values. Keep in mind, null is neither an object or a type. It is a special value that can be assigned to a reference type.
  • Arraylists inherits class: An arraylist will inherit the AbstractList class. It will
    also implement the List interface.
  • Arraylists are an ordered collection: An arraylist is an ordered collection. As new elements are added the arraylist will maintain the order of elements. The arraylist allows random access to the list.
  • Arraylists and boxed types: An arraylist can be created using only boxed types, and not primitive types. Boxed types are data that can be wrapped in an object, so the data can be manipulated like an object. Primitive data types cannot be boxed, will not be treated like an object, and cannot have the characteristics of an object. Char and boolean are examples of primitive data types. Boxed data types can be automatically converted into an object and will be treated like an object with all the characteristics of an object. An Integer or Boolean are examples of boxed data types.
  • Arraylistsand synchronization: An arraylist is not synchronized. This means that when multiple threads are modifying the arraylist at the same time, the results will be nondeterministic. Deterministic results in Java are guaranteed and predictable. Nondeterministic results incorporate random, chaotic elements and cannot be predicted.

Arraylists are a powerful tool in Java programming. Because they create a dynamic array, they do require more memory and processing power than a standard array in Java. As long as you keep in mind the strengths and capabilities of the arraylist, they are a strong addition to your programming.

Constructors in Arraylist Java

Let’s dive into how you can implement arraylist java in your java programming.

We’ll start by looking at constructors for an arraylist java. A constructor in Java is a block of code that creates an instance of a class. In this case, an arraylist that can be filled with elements. Constructors for an arraylist include:

  • ArrayList(): This constructor builds an empty arraylist.
  • ArrayList(Collection c): With this constructor, the arraylist is initially populated with elements from collection c.
  • ArrayList(int capacity): This constructor will build an arraylist with a specified initial, or starting, capacity. Additional elements can be added after
    creation, and elements can also be removed to adjust the capacity.

Constructors are used to initially implement an arraylist, or dynamic array, in a program.

Methods in Arraylist Java

A method in Java is a block of statements that perform a function or task in Java. Methods are an easy way to reuse code. They simplify and save time in the coding process.

Let’s look at a few common methods for arraylist Java:

  • void clear(): This method removes all elements from the arraylist.
  • void add(int index, Object element): Use this method to insert a specific element in a specific index position in the arraylist.
  • Object clone(): With this method, you can return a shallow copy of the arraylist.
  • Object[] to Array(): Use this method to return an array that contains every element in the list in the correct order.
  • Boolean addAll(Collection C): This method will append every element from a collection to the end of the arraylist. The order that the values are returned is specified by the collection’s iterator.
  • Boolean add(Object 0): With this method, append a specified element to the end of the arraylist.

A Final Word on Arraylist Java

Java has become one of the most widely-used programming languages in the world. Java programmers are in-demand with many of the top businesses.

Arraylist Java and dynamic arrays are a fundamental tool in Java. Make sure to familiarize yourself with the capability and rules of arraylists.

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What Is the C++ Vector Function?

Photo of computer screen with program code displayed in classic hacker color. Shallow depth of field places word "lexical" in focus

Spend some time talking to developers, and each has their favorite language. Many are happy to talk about SQL, Ruby/Rails, Swift, or Java as their favorite programming language. Ask them what their second favorite language is and the answer is almost always C++.

Many developers insist C++ is the best language for managing complex operations. It delivers very reliable performance for intricate operations, with a small programming footprint and low-energy.

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But it’s also a very complex and demanding language. It’s not a language for easy work, simple apps, or junior developers. The power of C++ requires programming skill and developer acumen and experience.

The C++ Vector is a powerful bit of functionality in the developer’s toolbox. We’ll look at how the C++ vector function works, how it can be used.

Let’s get started.

The History of ​​C++

C++ is an older language, first developed in 1979 by Bjarne Stroustrup. Stroustrup was working with the Simula 67 language at the time, a language widely thought to be the first object-oriented programming language. He felt Simula 67, while a useful language, was too slow for general programming.

Stroustrup began developing a new language known as “C with Classes” to add the object-oriented programming to the C language. C was a popular language, widely respected for portability, speed and functionality. Stroustrup added functions to C that included classes, inheritance, inlining, and default function arguments.

student typing on laptop

In 1983, the ++ was added to C to denote the ++operator for incrementing a variable. This helped identify the strength of the language. Additional features were added to C++, including function overloading, references with the & symbol, virtual functions, and the const keyword.

Since then, C++ has become a useful language for general-purpose programming. Many popular programs are written in C++, including Adobe applications, programs in Microsoft, and parts of the Mac OS.  Applications that require high-performance, eking out every bit of performance from a CPU, also rely on C++. This includes audio/video processing, 3D rendering, and fast, or twitch, game development.

This is why many mainstream games and gaming companies rely on C++Popular
apps
like Facebook and Amazon also use C++. C++ also eliminates resources when released to increase performance, making it the right choice for industries like finance, high-performance manufacturing, real-time systems and transportation.

Let’s look at how vectors work in C++.

What is a C++ Vector?

A vector in C++ acts as a data storage unit, sequence container, and a dynamic array. As elements are added to the array, the vector will automatically resize itself to accommodate the new element. When elements are removed, the vector will adjust.

A typical array in C++ is fixed in size and contains sequential elements all of the same type. They are used to store data. Arrays always use connected memory locations. The
lowest address is assigned to the first element, and highest address is assigned to the last element. Since the array is of a fixed size, the number of elements must be determined when the array is created.

Vectors work like an array, but don’t have a fixed size.  The vector will adjust as needed
to accommodate data as it is added and removed. In practice, a vector will use more memory than a similarly-sized array to accommodate expected growth, but it does efficiently and dynamically grow to incorporate new data as needed.

Properties of a C++ Vector

A vector container in C++ has certain properties. These include:

  • Linear sequence: Elements in a vector in C++ have a strict linear sequence. Each element in the sequence can be accessed by their position in the sequence.
  • Dynamic access: A vector permits direct access to any element in the container. The vector enables rapid addition and removal of elements at the end of a sequence.
  • Allocator-aware: The vector uses allocators to manage storage needs. An allocator is part of the C++ Standard Library and manages requests for the allocation and deallocation of memory for data containers.

Implementation of a C++ Vector

The types of elements that can be stored by the vector depend on how the vector is initialized. Remember, all elements in a vector must be of the same type. Vectors can store string, float, and int elements.

Selecting an allocator object when implementing a vector will also define the storage allocation model. By default, an allocator class template is used. This assigns the simplest memory allocation model. This model is value-independent.

Iterators for C++ Vector

An iterator is a fundamental part of the C++ Standard Template Library. Iterators are used to access the data stored in the vector. They point to the specific element within
the data storage unit or container.

Let’s look at some common iterators for vectors in C++:

  • begin: Using the begin iterator will return the element in the beginning of the sequence in the vector.
  • end: The end iterator will return the element at the end of the dynamic array, or the theoretical element that follows the last element.
  • rbegin: This will return the reverse iterator to the reverse beginning of the vector. This will move from the last element to the first element.
  • rend: This will return the reverse iterator. It points to the theoretical element immediately before the first element in the sequence. It is the reverse end of
    the vector.
  • cbegin: Using the cbegin iterator will return the const_iterator to the beginning. A const_iterator can be used for accessing the elements in the container and cannot be used to modify the data.
  • cend: Using the cend iterator will return the const_iterator to the end. A const_iterator can be used for accessing the elements in the container and
    cannot be used to modify the data.
  • crbegin: This will return a const_reverse_iterator to the reverse beginning of the dynamic array.
  • crend: This will return a const_reverse_iterator to the reverse end of the dynamic array.

C++ Modifiers for a Vector

C++ Modifiers are another important feature in the programming language. When char, int, and double data types have modifiers preceding them, the base type can be modified. Modifiers can be used to adjust the type to fit programming situations.  

In general, a vector is more efficient than other dynamic sequence containers in C++, including deques, lists, and forward_lists. They are suited to adding or removing elements from the end of the sequence. They are less efficient at inserting or removing
elements within the sequence.

C++ Modifiers that can be used on elements in a vector include:

  • assign: The assign modifier will assign data or content to the vector, adding the element to the container.
  • push_back: This modifier will add the element it modifies to the end of the sequence in the container.
  • pop_back: Use the pop_back modifier to delete the last element in the sequence, shrinking the vector.
  • insert: The insert modifier will insert the specific modified elements to the sequence.
  • erase: The erase modifier is used to delete or eliminate specific elements in the sequence.
  • swap: Use the swap modifier to move content inside the sequence.
  • clear: The clear modifier will remove, or clear, content inside a sequence. It uses the location within the sequence, rather than the element.
  • emplace: Use emplace to construct, or build, an element and the insert it within the sequence.
  • emplace_back: The emplace_back modifier is used to construct an element and insert it at the end of the sequence.

Calculating Vector Capacity in C++

The capacity function is a built-in function in C++ which can be used to calculate the storage assigned to the vector. The capacity is expressed as the number of elements.

Keep in mind the capacity that is returned is not necessarily equal to the number of elements in the vector. Extra space will often be assigned to a vector to accommodate growth. This way, the system won’t need to reallocate memory every time an element is added to the sequence.

Capacity also doesn’t limit the size of the vector. Adding elements will automatically expand the size of the dynamic array as needed. A limit to the size of a vector is a property of the member max_size.

Functions on capacity for vectors in C++ include:

  • size(): Calculates the number of elements in the vector.
  • max_size(): Calculates the maximum number of elements a vector can contain.
  • capacity(): Calculates the storage space currently assigned, or allocated, to the vector. This is expressed as the number of elements.
  • resize(): This can be used to resize the vector to contain a specific number (“g”) of elements.
  • empty(): Determine if a container, or vector, is empty of all elements.
  • shrink_to_fit(): Used to limit the capacity of a vector. The container will be shrunk, and all elements beyond the capacity will be destroyed.
  • reserve(): A request to assign enough vector capacity to contain at least a specific number of elements.

A Final Word on Vectors in C++

Vectors, or dynamic arrays, are a powerful tool for storing and accessing information in C++. As more and more companies are using C++ to store and use data, demand for programmers knowledgeable in C++ will only increase.

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