java新手笔记13 继承

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();

	}

}