Java でコールバックの簡単サンプル

interface Callback{
    void call();
}

class A implements Callback{
    private B b;

    public A(){
        b = new B();
        b.registerCallback(this);
    }    

    // Implementation of the callback interface
    public void call(){

    }
}

public class B
{
    private Callback callbackoNotify;

    public class registerCallback(Callback callback)
    {
        callbackoNotify = callback;
    }

    public void doTask()
    {  
        //do some stuff...
        callbackNotify.call();
    }
}