【JavaSE】java实现闭包与回调

java实现闭包与回调

closure是一个可被调用的对象，它记录一些信息，这些信息来自于创建它的作用域。
通过内部类实现闭包是java提供优良解决方案。参考《Think in java》p207

Callee1直接实现Increment接口
Callee2通过内部类实现接口

package com.huat.callback;

interface Incrementable {
    void increment();
}

class Callee1 implements Incrementable {

    private int i = 0;
    @Override
    public void increment() {
    i++;
    System.out.println(i);
    }

}

class MyIncrement {
    public void increment() {
    System.out.println("other operration");
    }

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

    }
}


class Callee2 extends MyIncrement {
    private int i = 0;
    public void increment() {
    super.increment();
    i++;
    System.out.println(i);
    }

    private class Closure implements Incrementable {

    @Override
    public void increment() {
        // TODO Auto-generated method stub
        Callee2.this.increment();
    }

    }

    Incrementable getCallbackReference () {

    return new Closure();
    }
}


class Caller {

    private Incrementable callbackReference;
    Caller (Incrementable cbh) {
    callbackReference = cbh;
    }
    void go () {
    callbackReference.increment();
    }

}

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();

    }
}