JavaSE-12.1.3【接口名作为形参和返回值】

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package day3.yub4by01.p3;   /* 1.3 接口名作为形参和返回值       方法的形参是接口名，其实需要的是该接口的实现类对象     方法的返回值是接口名，其实返回的是该接口的实现类对象    */   public class JumppingDemo {       public static void main(String[] args) {         JumppingOperator jo = new JumppingOperator();         Jumpping j = new Cat();         jo.useJumpping(j);           Jumpping j2 = jo.getJumpping(); //new Cat();         j2.jump();     }   }

　　

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package day3.yub4by01.p3;   public class JumppingOperator {       public void useJumpping(Jumpping j){ //多态Jumpping j = new Cat();         j.jump();     }       public Jumpping getJumpping(){         Jumpping j = new Cat();         return j;     }   }

　　

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package day3.yub4by01.p3;   public interface Jumpping {       void jump();   }

　　

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package day3.yub4by01.p3;   public class Cat implements Jumpping{     @Override     public void jump() {         System.out.println("猫猫会跳高吗");     } }