1.重载必须在同一各类中吗？
Overloading in Java can occur when two or more methods in the same class share the same name
 or even if a child class shares a method with the same name as one of it’s parent classes.
2.重写必须在不同类中吗？
public class Test{
   public static void main(String[] args){
        System.out.println(new Test());
       System.out.println(new Test(){
        public String toString(){
             return "manual override";
         }
       });
      System.out.println(new Test(){
                public String gm(){
                    return  "manual gm";
               }
        }.gm());
     }  //end of main method

   public String gm(){
     return "gm";
    }
}