In Java, what does the finally block do?
The finally block, if used, is placed after a try block and the catch blocks that follow it. The finally block contains code that will be run whether or not an exception is thrown in a try block. The general syntax looks like this:
public void someMethod{
Try {
// some code
}
Catch(Exception x) {
// some code
}
Catch(ExceptionClass y) {
// some code
}
Finally{
//this code will be executed whether or not an exception
//is thrown or caught
}
}
There are 4 potential scenarios here:
1. The try block runs to the end, and no exception is thrown. In this scenario, the finally block will be executed after the try block. 2. An exception is thrown in the try block, which is then caught in one of the catch blocks. In this scenario, the finally block will execute right after the catch block executes. 3. An exception is thrown in the try block and there's no matching catch block in the method that can catch the exception. In this scenario, the call to the method ends, and the exception object is thrown to the enclosing method - as in the method in which the try-catch-finally blocks reside. But, before the method ends, the finally block is executed. 4. Before the try block runs to completion it returns to wherever the method was invoked. But, before it returns to the invoking method, the code in the finally block is still executed. So, remember that the code in the finally block willstill be executed even if there is a return statement somewhere in the try block.
You can also read more about how the finally block will run after a return statement here – along with some good code samples: Will finally run after return?