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;
    }
}