Java内部类(5)：应用例

例1-闭包(Closure)

闭包是一个可调用的对象(通过Callback)，它记录了一些信息，这些信息来自于创建它的作用域

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 operation");
    }

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

class Callee2 extends MyIncrement {
    private int i = 0;

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

    private class Closure implements Incrementable {
        @Override
        public void increment() {
            Callee2.this.increment();
        }
    }

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

class Caller {
    private Incrementable callbackReference;

    Caller(Incrementable callbackReference) {
        this.callbackReference = callbackReference;
    }

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

/**
 * 关键字: 内部类应用, 闭包(Closure)<br/>
 * 1.闭包是一个可调用的对象(通过Callback)，它记录了一些信息，这些信息来自于创建它的作用域<br/>
 */
public class Test007 {

    public static void main(String[] args) {
        Callee1 c1 = new Callee1();
        c1.increment(); // 1
        Callee2 c2 = new Callee2();
        MyIncrement.f(c2); // Other operation|1
        Caller caller1 = new Caller(c1);
        caller1.go(); // 2
        Caller caller2 = new Caller(c2.callBack());
        caller2.go(); // Other operation|2
    }
}

例2-复杂情况下的调用顺序

class Egg2 {

    protected class Yolk {
        public Yolk() {
            System.out.println("Egg2.Yolk()");
        }

        public void f() {
            System.out.println("Egg2.Yolk.f()");
        }
    }

    private Yolk y = new Yolk();

    public Egg2() {
        System.out.println("New Egg2()");
    }

    public void insertYolk(Yolk yy) {
        y = yy;
    }

    public void g() {
        y.f();
    }
}

class Test008Sub extends Egg2 {
    public Test008Sub() {
        System.out.println("AA");
        insertYolk(new Yolk());
    }

    public class Yolk extends Egg2.Yolk {
        public Yolk() {
            System.out.println("BigEgg2.Yolk()");
        }

        public void f() {
            System.out.println("BigEgg2.Yolk.f()");
        }
    }
}

// 复杂情况下的调用顺序
public class Test008 {
    public static void main(String[] args) {
        new Test008Sub().g();
        // Egg2.Yolk()
        // New Egg2()
        // AA
        // Egg2.Yolk()
        // BigEgg2.Yolk()
        // BigEgg2.Yolk.f()
    }
}