1、Person类

package com.yfs.javase;//可以有多个子类public class Person {	private String name;// 私有属性不能继承	private int age;	private char sex;	private void privateMehtod() {// 私有方法 类中可以访问		System.out.println("call privateMehtod()...");	}	public Person() {		// privateMehtod();		System.out.println("创建Perosn对象...");	}	public Person(String name) {		this.name = name;	}	public Person(String name, int age, char sex) {		this.name = name;		this.age = age;		this.sex = sex;	}	public void introduce() {		System.out.println("I am Person....");	}	public String toString() {		return "姓名：" + name + "  年龄 ：" + age + "  性别：" + sex;	}	public void speak() {		System.out.println(name + " 工作了吗？");		// privateMehtod();	}	public void sleep() {		System.out.println(name + " 睡觉了吗？");	}	public void eat() {		System.out.println(name + " 吃了吗？");	}	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 char getSex() {		return sex;	}	public void setSex(char sex) {		this.sex = sex;	}}

 2.Student类

package com.yfs.javase;//实现代码重用  单继承public class Student extends Person {// 继承Person	private int score;	@Override	public void introduce() {		System.out.println("I am student...");	}	// 覆盖 重写父类的方法	@Override	public String toString() {		return super.toString() + "  成绩：" + score;	}	public int getScore() {		return score;	}	public void setScore(int score) {		this.score = score;	}	public Student() {// 系统自动调用父类构造方法		// super();//调用父类无参数构造方法super()  必须第一句		// super("Jack");		System.out.println("创建Student对象...");	}	// 扩展方法	public void study() {		// getName()继承方法		// privateMethod();私有方法不能继承		// super.toString();//调用父类方法		// this super		System.out.println(getName() + " 在学习...");// 私有属性能否继承	}}// 子类下还可以继承class YfsStudent extends Student {}

 3.Teacher类

package com.yfs.javase;public class Teacher extends Person {	@Override	public void introduce(/*int a*/) {		System.out.println("I am teacher...");	}}

4.Person测试

package com.yfs.javase;public class PersonTest {	public static void main(String[] args) {		Person p1 = new Person();		p1.setName("张三");		p1.setAge(20);		p1.setSex('男');		System.out.println(p1);//默认toString方法				Student s1 = new Student();		s1.setName("李四");		s1.setAge(22);		s1.setSex('女');		System.out.println(s1);				Teacher t1 = new Teacher();		t1.setName("王五");		t1.setAge(30);		t1.setSex('男');		System.out.println(t1);				YfsStudent ys = new YfsStudent();		ys.setName("Tom");		System.out.println(ys);		//ys.				s1.study();		//p1.study();//父类不能调用子类方法		ys.study();	}}

 5.Student测试

package com.yfs.javase;public class StudentTest {	public static void main(String[] args) {		//构造方法不能继承		//Student s1 = new Student("zhangsan",20,'男');				//Student s2 = new Student("lisi");				Student s3 = new Student();//系统提供构造方法		s3.setName("李四");		s3.speak();		System.out.println(s3);		s3.eat();				Teacher t1 = new Teacher();		t1.setName("张飞");		t1.eat();		System.out.println(t1);		//Person p1 = new Person("张三",23,'男');	}}

 6.Teacher类测试

package com.yfs.javase;public class TeacherTest {	public static void main(String[] args) {		Person p1 = new Person();		p1.setName("张三");				Student s1 = new Student();		s1.setName("李四");				Teacher t1 = new Teacher();		t1.setName("王五");				p1.introduce();		s1.introduce();		t1.introduce();	}}