Question

Why do I need to declare a local variable as final if my Inner class defined within the method needs to use it ?

Example :

class MyOuter2 {

private String x = "Outer2";

void doStuff() {
    final String y = "Hello World";

    final class MyInner {

        String z = y;

        public void seeOuter() {
            System.out.println("Outer x is "+x);
            System.out.println("Local variable is "+y);
            MyInner mi = new MyInner();
            mi.seeOuter();
        }
    }
}

}

Why the String y needs to be a final constant ? How does it impact ?

Answer 1

The answer is the two are in different scopes. So that variable could change before the inner class accesses it. Making it final prevents that.