1.

package test;

interface Dongwu {

    void eat();

}

2.

package test;

public class Gou implements Dongwu{

    public void eat() {

        // TODO Auto-generated method stub

        System.out.println("我是小狗");

    }

}

3.

package test;

public class Mao implements Dongwu{

    @Override

    public void eat() {

        // TODO Auto-generated method stub

        System.out.println("我是小猫");

    }

    

}

4.

package test;

public class ADongwu implements Dongwu{

    private Dongwu dongwu;

    public ADongwu(Dongwu dongwu) {

        // TODO Auto-generated constructor stub

        this.dongwu = dongwu;

    }

    @Override

    public void eat() {

        // TODO Auto-generated method stub

        System.out.println("A家的动物吃饭前要先跑一跑");

        dongwu.eat();

    }

    

}

5.

package test;

public class BDongwu implements Dongwu{

    private Dongwu dongwu;

    public BDongwu(Dongwu dongwu) {

        // TODO Auto-generated constructor stub

        this.dongwu = dongwu;

    }

    @Override

    public void eat() {

        // TODO Auto-generated method stub

        System.out.println("B家的动物吃饭先要先跳一跳");

        dongwu.eat();

    }

}

6.

package test;

public class Test {

    public static void main(String args []) {

        Gou gou = new Gou();

        ADongwu a = new ADongwu(gou);

        a.eat();

        

        Gou gou2 = new Gou();

        BDongwu b = new BDongwu(gou2);

        b.eat();

    }

}