 public class ClassA
{
      ClassA()
      {
         System.out.println("instance of ClassA");
      }
      public class InnerA extends ClassA   //õڲ
{
          InnerA()
          {
System.out.println("this is a public instance of InnerA");
          }
       }// end of InnerA
      private static class InnerB        //˽еڲ
      {
          static int counter ;
          InnerB()
          {
System.out.println("this is a private instance of InnerB");
counter++;       
}
          static int getCounter()
          {
             return counter;
          }
      }// end of InnerB
      protected class InnerC          //ܱڲ
      {
          InnerC()
          {
System.out.println("this is a protected instance of InnerC : " + name);
          }
          static final String name = "inner C";
     }// end of InnerC
}
