package innerclasses;

/**
 * RUN:
 *         javac innerclasses/Callbacks.java && java innerclasses.Callbacks
 * OUTPUT:
 *         Other operation
 *         1
 *         1
 *         2
 *         Other operation
 *         2
 *         Other operation
 *         3
 */

public class Callbacks {

    public static void main(String[] args) {
        Callee1 c1 = new Callee1();
        Callee2 c2 = new Callee2();
        MyIncrement.f(c2);

        Caller caller1 = new Caller(c1);
        Caller caller2 = new Caller(c2.getCallbackReference());

        caller1.go();
        caller1.go();
        caller2.go();
        caller2.go();
    }
}

interface Incrementable {
    void increment();
}

class Callee1 implements Incrementable {

    private int i = 0;

    public void increment() {
        i++;
        System.out.println(i);
    }
}

class MyIncrement {

    public void increment() { System.out.println("Other operation"); }

    public static void f(MyIncrement mi) { mi.increment(); }
}

class Callee2 extends MyIncrement {

    private int i = 0;

    /* private */ public void increment() {
        super.increment();
        i++;
        System.out.println(i);
    }

    private class Closure implements Incrementable {

        public void increment() {
            Callee2.this.increment();
        }
    }

    Incrementable getCallbackReference() {
        return new Closure();
    }
}

class Caller {

    private Incrementable callbackReference;

    Caller(Incrementable cbh) { callbackReference = cbh; }

    void go() { callbackReference.increment(); }
}