JAVA新手入门手稿——类的创建、继承与多态

package com.niu.demo;

public class Extends_{
	
	public static void main(String[] args){
		Manager niu = new Manager("Niu",18);
		System.out.println(niu.toString());
		
		//父类多态引用子类
		Employee zhang = new Manager("zhang",20);
		Employee li = new Employee("li",17);
		niu.doWork();
		zhang.doWork();
		li.doWork();
		
		//instanceof测试对象是否相同或者有继承关系
		System.out.println(niu instanceof Employee);
		System.out.println(niu instanceof Manager);
		System.out.println(li instanceof Manager);
	}
}


//继承Employee类，私有方法之外的方法将会自动继承
class Manager extends Employee{
	
	public Manager(String name,int age){
		//调用父类构造
		super(name,age);
	}
	
	//重写父类方法
	public void doWork(){
		
		System.out.println("Manager is work!");
	}
}

class Employee{
	
	private String Name;
	private int Age;
	
	//静态与常量
	private static int count = 0;
	private final static String sex = "man";
	
	//实例化块,不是必须的
	{
		//this.Name = "default";
	}
	//默认构造
	public Employee(){
		
		this.Name = "default";
		this.Age = 0;
	}
	
	//带参构造
	public Employee(String name,int age){
		
		//构造器调用构造器
		//this()
		this.Name = name;
		this.Age = age;
		this.count++;
	}
	
	//访问器方法
	public String getName(){
		
		return this.Name;
	}
	
	public int getAge(){
		
		return this.Age;
	}
	
	//修改器方法
	public void setName(String name){
		
		this.Name = name;
	}
	
	//静态方法只能访问静态成员
	public static int getCount(){
		
		return count;
	}
	
	public void doWork(){
	
		System.out.println("Employee is work");
	}
	
	//重写Object的方法
	public String toString(){
		
		return "name: "+this.Name+" age: "+this.Age;
	}
	
	//重载toString方法
	public String toString(int age){
		
		return "name: "+this.Name+" age: "+age;
	}
	
}