java基础

 1 public class A {
 2     int  a=1;
 3     double  d=2.0;
 4      void  show( )
 5         {
 6             System.out.println("Class A: a="+a +"\t d="+d);
 7         }
 8      public static void main(String[] args) {
 9             A a=new A();
10             a.show();
11             A b=new B();
12             b.show();
13         }
14     }
15      class  B  extends  A{
16          float  a=3.0f;               
17             String  d="Java program.";  
18           void  show( )                 
19           { 
20                 super.show( );      
21                 System.out.println("Class B:  a="+a +"\t d="+d);
22           }
23      }