抽象的理解

package package1;

public class Demo12 {
public static void main(String[] args) {
	javaTeacher javaTeacher=new javaTeacher(20, "张三", 5000);
	javaTeacher.work();
	/*
	 *抽象类不能被实例化
	 * Employee employee=new Employee(20, "张三", 5000);
	 * */
	Leader leader=new Leader(20, "王五", 5000,1000);
	//向下转型
	leader.work();
	Employee emp=new Leader(20, "王五", 5000,1000);
	emp.work();
}
}
//抽象类
abstract class Employee{
	private int number;
	private String name;
	private double salary;
	public Employee(int number,String name,double salary) {
		this.name=name;
		this.number=number;
		this.salary=salary;
	}
	//抽象方法
	public abstract void work();
	//可实现的方法
	public  void aa() {}  //抽象类中能够有抽象方法也能够有可实现的方法
}
//一个类继承了抽象类，那么这个类要么实现抽象类中的方法，要么继续抽象下去
class Leader extends Employee{
	//私有属性
	private double allowance;//津贴
	public Leader (int number,String name,double salary,double allowance) {
		super(number, name, salary);
		this.allowance=allowance;
	}

	@Override
	public void work() {
		// TODO Auto-generated method stub
		System.out.println("培训新员工");
		System.out.println("设计课程");
	}
	/*
	 *继续抽象下去的表现
	 * public abstract void work() {}
	 * */
}
class javaTeacher extends Employee{
	public javaTeacher (int number,String name,double salary) {
		super(number, name, salary);
	}
	@Override
	public void work() {
		// TODO Auto-generated method stub
		System.out.println("上java课程");
	}
}