java--继承

继承是子类对父类的一些属性、方法的继承，即子类可以使用父类的属性，方法。

//学生类
package com.situ.chaptertest;

public class Student {
    private String name;//私有属性
    private String sex;
    private int age;
    
    public void sayHello() {
	System.out.println("你好！");
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }

    public Student(String name, String sex, int age) {
	this.name = name;
	this.sex = sex;
	this.age = age;
    }

    public Student() {
	// TODO 自动生成的构造函数存根
	
    }

    @Override
    public String toString() {
	return "Student [name=" + name + ", sex=" + sex + ", age=" + age + "]";
    }
    
   
    
    
}

//初中生类 继承 学生类的姓名 性别 年龄
package com.situ.chaptertest;

public class JuniorStudent extends Student{
    private int id;
    private String classname;
    private String schoolname;
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getClassname() {
        return classname;
    }
    public void setClassname(String classname) {
        this.classname = classname;
    }
    public String getSchoolname() {
        return schoolname;
    }
    public void setSchoolname(String schoolname) {
        this.schoolname = schoolname;
    }
    public JuniorStudent(String name, String sex, int age, int id, String classname, String schoolname) {
	super(name, sex, age);//继承父类的属性方法
	this.id = id;
	this.classname = classname;
	this.schoolname = schoolname;
    }
    @Override
    public String toString() {
	return "JuniorStudent [id=" + id + ", classname=" + classname + ", schoolname=" + schoolname + ", getId()="
		+ getId() + ", getClassname()=" + getClassname() + ", getSchoolname()=" + getSchoolname() + "]";
    }
   
    
    
}

//测试类给new的初中生赋值
package com.situ.chaptertest;

public class Test {

    public static void main(String[] args) {
	// TODO 自动生成的方法存根
	Student s = new Student();
	JuniorStudent j =new JuniorStudent("q", "w", 1, 2, "e"," r");
	
	System.out.println(j);
	System.out.println(s);//未对s赋值，所以输出为空
	s.sayHello();
    }

}

运行截图：

继承即子类在父类的基础上加上自己的特性