【Java每日一题】20170118

package Jan2017;  
  
import java.util.List;  
  
public class Ques0118 {  
  
}  
  
class Parent{  
    public Parent method1(){  
        return new Parent();  
    }      
          
    public void method2(Parent parent){  
  
    }  
}  
      
class Sub extends Parent{      
    @Override  
    public Sub method1(){  
        return new Sub();  
    }  
  
    @Override  
    public void method2(Sub sub){  
  
    }  
}