Modify local variable from anonymous inner class

Question

I found that we can't modify local variables from inner class as it's defined as final. While reading I found that we have to mark it as final so it does not create any value mismatch issue. But what if we really want to modify the local variable from inner class. Is there any work around?

Answer 1

You can't modify the local variable. But if the local variable is an object reference, you can modify the object it refers to. For example:

public static void main(String[] args) {
    final AtomicReference<String> value = new AtomicReference<String>("hello");

    System.out.println(value); // prints "hello"

    new Runnable() {
        public void run() { value.set("goodbye"); }
    }.run();

    System.out.println(value); // prints "goodbye"
}