Java学习笔记------接口-编程知识

Java学习笔记------接口

接口

接口就是一种规则,对行为的抽象

定义和使用接口

用关键字interface来定义，public interface 接口名{}

接口不能实例化

接口和类之间是实现关系，通过impls关键字表示

public class 类名 implements 接口名{}

接口的子类（实现类），要么重写接口中所有的抽象方法，要么是抽象类

注意：

接口和类是实现关系，可以单实现，也可以多实线

public class 类名 implements 接口名1，接口名2{}

实现类还可以在继承类的同时实现多个接口

public class 类名 extends 父类 implements 接口名1，接口名2{}

练习

代码：

package com.test.demo1;public abstract class Animal {private String name;private int age;public Animal() {}public Animal(String name, int age) {this.name = name;this.age = age;}/*** 获取* @return name*/public String getName() {return name;}/*** 设置* @param name*/public void setName(String name) {this.name = name;}/*** 获取* @return age*/public int getAge() {return age;}/*** 设置* @param age*/public void setAge(int age) {this.age = age;}public abstract void eat();public String toString() {return "Animal{name = " + name + ", age = " + age + "}";}
}

public class Dog extends Animal implements Swim{public Dog() {}public Dog(String name,int age) {super(name, age);}@Overridepublic void eat() {System.out.println("狗吃骨头");}@Overridepublic void swim() {System.out.println("狗刨式游泳");}public String toString() {return "Dog{}";}public void look_home(){System.out.println("小狗"+this.getName()+"在看家");}
}

public class Frog extends Animal implements Swim{public Frog() {}public Frog(String name,int age) {super(name, age);}@Overridepublic void eat() {System.out.println("青蛙吃虫子");}@Overridepublic void swim() {System.out.println("青蛙在游泳");}public String toString() {return "Frog{}";}
}

public class Rabbit extends Animal {public Rabbit() {}public Rabbit(String name,int age) {super(name, age);}@Overridepublic void eat() {System.out.println("兔子在吃草");}public String toString() {return "Rabbit{}";}
}

public interface Swim {public abstract void swim();
}

public class test {public static void main(String[] args) {Rabbit r=new Rabbit("小白",2);System.out.println("兔子"+r.getName()+"年龄为"+r.getAge());r.eat();Dog d=new Dog("小黑",4);System.out.println("狗子"+d.getName()+"年龄为"+d.getAge());d.eat();d.swim();d.look_home();Frog f=new Frog("小青",1);System.out.println("青蛙"+f.getName()+"年龄为"+f.getAge());f.eat();f.swim();}
}

运行结果：