java 对象的上转型对象(父类)

class  类人猿 {
   void crySpeak(String s) {
       System.out.println(s); 
   }  
}
class People extends 类人猿 {
   void computer(int a,int b) { 
      int c=a*b;
      System.out.println(c); 
   }
   void crySpeak(String s) {
      System.out.println("***"+s+"***"); 
   }  
}
public class Example5_10 {
   public static void main(String args[]) {
      类人猿 monkey=new People();   //monkey是People对象的上转型对象
      monkey.crySpeak("I love this game");
      People people=(People)monkey; //把上转型对象强制转化为子类的对象
      people.computer(10,10);
   }
}