方法重写（静态和非静态有区别）多态

main

public class Main
{
    public static void main(String[] args)
    {
        //方法的调用只和左边定义的数据类型有关
        stu s=new teacher();
        s.say();//stu,如果不加static，子类重写父类的方法输出teacher
    }

}

stu父类

public class stu 
{  public static void say()
    {
        System.out.println("stu");
    }
}

teacher子类

public class teacher extends stu{
    public static void say()
    {
        System.out.println("teacher");
    }
}