java继承 、方法重写、重写toString方法

1.Java的继承，关键词Extends

 package cn.mwf.oo;

 public class TextExtends {
     public static void main(String[] args) {
         Student s = new Student("侠客小飞", 60, "计算机科学与技术");
         s.rest();
         s.study();
     }

 }
 class Person{
     String name;
     int height;
     public void rest() {
         System.out.println("休息一会！");
     }
 }
 class Student extends Person{
     String major;//专业
     public void study() {
         System.out.println("在图书管学习java！");
     }
     public Student(String name,int height,String major) {
         this.name = name;
         this.height = height;
         this.major = major;
     }
 }

2.方法的重写

 package cn.mwf.oo;
 //方法的重写
 public class TestOverride {
     public static void main(String[] args) {
         Vehicle v1 = new Vehicle();
         v1.run();
         v1.stop();
         Vehicle v2 = new Hourse();
         v2.run();
         v2.stop();
         Vehicle v3 = new Airplane();
         v3.run();
         v3.stop();
     }
 }
 //Vehicle类
 class Vehicle{
     public void run() {
         System.out.println("跑···");
     }
     public void stop() {
         System.out.println("停止···");
     }
 }
 //Hourse类继承Vehicle类
 class Hourse extends Vehicle{
     public void run() {
         System.out.println("嘚嘚嘚的跑");
     }
 }
 //Airplane类继承Vehicle类
 class Airplane extends Vehicle{
     public void run() {
         System.out.println("在空中飞");
     }
     public void stop() {
         System.out.println("在空中不能停，会掉下来");
     }
 }

3.重写toString方法

 package cn.mwf.oo;

 public class TestObject {
     public static void main(String[] args) {
         TestObject to = new TestObject();
         System.out.println(to.toString());

         Person2 p2 = new Person2("茜茜",6);
         System.out.println(p2.toString());
     }
     public String toString() {
         return "测试Object对象";
     }
 }
 class Person2{
     String name;
     int age;

     public String toString() {
         return name+",年龄:"+age;
     }
     public Person2(String name, int age) {
         this.name = name;
         this.age = age;
     }
 }