anonymous inner class not affect outer class member

Question

the output is

   foo
   foo

but I was expecting it to be

    foo 
    bar
    foo

I do not under stand why the inner class does not work

class Test {

    private String foo = "foo";

    public void method() {
        System.out.println(foo);
        new Object() {
            public void bar() {
                foo = "barr"; 
                System.out.println(foo); //not work

            }
        };

        System.out.println(foo);
    }

}


    public class Main {
        public static void main(String[] args){
        Test t=new Test();
        t.method();
      }
   }

You forgot to call the method: `new Object() { ... }.bar();` — shmosel, Aug 17 '17 at 05:57
You are written the code for printing the "barr" but it will not execute. — Sunil Kanzar, Aug 17 '17 at 06:00

score 0 · Answer 1 · answered Aug 17 '17 at 06:05

The output is actually:

foo

barr

If you correctly invoke the bar() function after creating the anonymous class:

class Test {

    private String foo = "foo";

    public void method() {
        System.out.println(foo);
        new Object() {
            public void bar() {
                foo = "barr";
                System.out.println(foo); 
            }
        }.bar();  // Added invocation here

        System.out.println(foo);
    }

}

public class Main {

    public static void main(String[] args) {
        Test t = new Test();
        t.method();
    }
}

score 0 · Answer 2 · answered Aug 17 '17 at 06:05

There is no call to the method bar() of the anonymous Object class. That is why the print statement inside it is never executed. You can update the code as below :

new Object() {
            public void bar() {
                foo = "barr"; 
                System.out.println(foo); //not work

            }
        }.bar();

to call the bar method. Now that you have executed this method where you assigned the instance variable foo to value "barr" , the last print statement in the method() will print the updated value "barr".

score 0 · Accepted Answer · answered Aug 17 '17 at 06:05

It will affect the outer member but code which made change in member variable must execute so your code should be like this:

public class Main {

    private String foo = "foo";

    public void method() {
        System.out.println(foo);
        new Object() {
            public void bar() {
                foo = "bar";
                System.out.println(foo);

            }
        }.bar();

        System.out.println(foo);
    }

    public static void main(String[] args) {
        Main t = new Main();
        t.method();
    }
}

And output :

foo
bar
bar

anonymous inner class not affect outer class member

3 Answers3