接口名作为形参和返回值

接口名作为形参:
建立jump接口、Cat、JumpOperator、JumpDemo类:
jump接口:

public interface Jump {
    void jump();
}

Cat类:

public class Cat implements Jump{

    public void jump(){
        System.out.println("猫会跳高");
    }
}

JumpOperator类:

public class JumpOperator {
    public void useJump(Jump j){
        j.jump();
    }
}

JumpDemo类:

public class JumpDemo {
    public static void main(String[] args) {
        JumpOperator jo1=new JumpOperator();
        Cat c1=new Cat();

        jo1.useJump(c1);
        }
}

接口名作为返回值:
建立jump接口、Cat、JumpOperator、JumpDemo类:
jump接口:

public interface Jump {
    void jump();
}

Cat类:

public class Cat implements Jump{

    public void jump(){
        System.out.println("猫会跳高");
    }
}

JumpOperator类:

public class JumpOperator {  
    public Cat useJump1(){
        Cat c1=new Cat();
        return c1;
    }
}

JumpDemo类:

public class JumpDemo {
    public static void main(String[] args) {
        JumpOperator jo2=new JumpOperator();
        Cat c2=jo2.useJump1();
        c2.jump();
    }
}

两段代码运行结果:
在这里插入图片描述

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