今日课堂回顾

package com.work;

public class father {
    
    private String name;
    private int age;
    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 Father()
//    {
//        System.out.println("父类的构造方法");
//    }
    public father (String name)
    {
        System.out.println("父类的有参的构造方法");
        this.name = name;
    }
    //工作
    public void work()
    {
        System.out.println("我劳动我光荣");
    }
}

 

package com.work;

public class Son extends father { 
    //Object a;所有类的父类
    
    public Son()
    {
        //super 表示父类
        super("儿子");
        System.out.println("子类的构造方法");
    }
    public void sing()
    {
        System.out.println("我喜欢唱歌");
    }
    //覆盖（重写）
    public void work()
    {
        //调用父类的方法
        //super.work();
        //System.out.println("我不喜欢上班，我要去参加海选");
        System.out.println("我边上班边练歌");
    }
    public static Object getData(int i)
    {
        Object rtn = null;
        //获取数据
        if (i==1)
        {
        //1 father
        father f = new father("向上转型的父类");
        //向上转型
        rtn = f;        
        }
        else
        {
        //2 son
        Son s = new Son();
        rtn = s;
        }
        return rtn;
    }
}

 

package com.work;

public class testjicheng {

    public static void main(String[] args) {
        // 
    father f = new father("父亲");
    
    f.setName("父亲");
    
    f.setAge(50);
    
    System.out.println("名字是："+f.getName()+"  年龄是："+f.getAge());
    
    f.work();
    
    Son s = new Son();
    
    s.setName("儿子");
    
    s.setAge(20);
    
    System.out.println("名字是："+s.getName()+"  年龄是："+s.getAge());
    
    s.work();
    
    s.sing();
        
    System.out.println();
        
    //转型
    
    //向上转型   子类转成父类
    
    father f1 = new Son();
    
    System.out.println("名字是："+s.getName());
    
    f1.work(); //如果被子类重写了，调用子类的方法
    
    System.out.println("向下转型");
    
    //向下转型  父类转成子类
    
    //Son s1 = (Son) new Father("父亲");
    
    Son s1 = (Son) f1;
    
    s1.work();
        
    System.out.println();
        
    father f2 = (father)Son.getData(1);
    
    f2.work();
    }
}