Java中的向上转型与向下转型

package jicheng;

public class free {
    public void sleep() {
        System.out.println("Human sleep..");
    }

    public static void main(String[] args) {
       free h = new Male();// 向上转型
        free h1 = new free();
        //h.speak();此时需要向下转型，否则不能调用speak方法。
         Male m = (Male) h;
         m.speak();
         /**Male m1 = (Male)h1;
         m1.speak();    此时会出现运行时错误，所以可以用instanceOF判断*/
       System.out.println(h1 instanceof Male);  
       if (h1 instanceof Male){
             Male m1 = (Male)h1;
             m1.speak();                 
         }
       System.out.println(h instanceof Male);  
       if (h instanceof Male){
           Male m1 = (Male)h;
           m1.speak();                   
       }
    }
}

class Male extends free {
    @Override
    public void sleep() {
        System.out.println("Male sleep..");
    }

    public void speak() {
        System.out.println("I am Male");
    }
}