接口的特点

简单接口

接口

package heima;

public interface Jumpping {
   public abstract void jump();
}

主函数

package heima;

public class JumppingDemo {
    public static void main(String[] args) {
        // Jumpping j=new Jumpping() ;接口不能实例化
        Jumpping j=new Cat();//运用多态进行实例化
        j.jump();


    }
}

继承接口的子类

package heima;

public class Cat implements Jumpping{
    @Override
    public void jump(){
        System.out.println("猫可以跳高");
    }
}

接口的实现与方法的调用

package lkj;

 interface Animal {
    int ID=1;
    void breathe();
    default void getType(String type){
        System.out.println("该动物属于："+type);
    }
    static int getID(){
        return Animal.ID;
    }

}

package lkj;

 class kkk {
    public static void main(String[] args) {
        System.out.println(Animal.getID());
        Dog dog=new Dog();
        System.out.println(dog.ID);
        dog.breathe();
        dog.getType("犬科");
    }
}

package lkj;

class Dog implements Animal{
    @Override
    public void breathe() {
        System.out.println("狗在呼吸");
    }

}

接口的成员特点

package heima;

public interface Inter {
public int num=10;
public final int num2=20;
public static final int num3=30;
//接口中默认修饰符
//等价于int num3=30;
//public Inter(){}接口没有构造方法只有成员方法
    //public Inter(){}
//public void show(){}接口里面不能有非抽象方法
    public abstract void method();
 void show();//默认存在public abstract


}

package heima;

public class InterfaceDemo {
    public static void main(String[] args) {
Inter i=new InterImpl();//利用多态创建接口
        //i.num=20;接口中的值默认被final修饰,所以接口中没有成员变量
        System.out.println(i.num);
        //i.num2=40;被final修饰不能重新赋值
        System.out.println(i.num2);
        System.out.println(Inter.num);//可以通过接口名直接访问说明他是被静态修饰
i.method();
i.show();



    }
}

package heima;

public class InterImpl extends Object implements Inter{
/*public InterImpl(){
  super();调用的不是接口而是Object类
}*/
@Override
public void method(){
    System.out.println("method");
  }
  public void show(){
      System.out.println("show");
  }


}

接口

案例：猫和狗

package heima;

public interface Jumpping {
    public abstract void jump();


}

package heima;

public class AnimalDemo {
    public static void main(String[] args) {
Jumpping j=new Cat();
j.jump();
        System.out.println("------------");
Animal a=new Cat();
a.setName("加菲");
a.setAge(5);
        System.out.println(a.getName()+","+a.getAge());
a.eat();
        ((Cat)a).jump();//Animal中没有jump
        a=new Cat("加菲",5);
        System.out.println(a.getName()+","+a.getAge());
a.eat();
        System.out.println("--------");
Cat c=new Cat();
c.setName("加菲");
c.setAge(5);
        System.out.println(c.getName()+","+c.getAge());
c.eat();
c.jump();




    }
}

package heima;

public abstract class Animal {
private String name;
private int age;
public Animal(){
}
    public Animal(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
    public abstract void eat();
}

package heima;

public class Cat extends Animal implements Jumpping{
  public void eat(){
      System.out.println("猫吃鱼");
  }
public void jump(){
    System.out.println("猫可以跳高了");
}

    public Cat() {
    }

    public Cat(String name, int age) {
        super(name, age);
    }
}

JAVA接口

接口的特点

接口的成员特点