Why Does Modifying a Variable in a `finally` Block Not Affect the Return Value in Java?

Why does modifying a variable in a finally block not affect the return value?

In Java, it's generally understood that the finally block should not affect the return value of the method. However, it may be confusing why this is the case, especially when the return value is modified within the finally block.

Consider the following example:

public class Test {

    private String s;

    public String foo() {
        try {
            s = "dev";
            return s;
        } 
        finally {
            s = "override variable s";
            System.out.println("Entry in finally Block");  
        }
    }

    public static void main(String[] xyz) {
        Test obj = new Test();
        System.out.println(obj.foo());
    }
}

The output of this code is:

Entry in finally Block
dev

Why is s not overridden in the finally block, yet the control printed output?

Explanation

The try block completes with the execution of the return statement. The value of s at the time the return statement executes is the value returned by the method. The fact that the finally clause later changes the value of s (after the return statement completes) does not (at that point) change the return value.

In the example above, the return statement in the try block sets the return value to "dev". The finally block then sets s to "override variable s", but this change occurs after the return value has already been set. Therefore, the return value is still "dev".

It's important to note that this behavior only applies to changes in the value of primitive variables or immutable objects. If s were a reference to a mutable object and the contents of the object were changed in the finally block, then those changes would be seen in the returned value.

The above is the detailed content of Why Does Modifying a Variable in a `finally` Block Not Affect the Return Value in Java?. For more information, please follow other related articles on the PHP Chinese website!