nested subclass java code example

Example 1: Nested classes in java

// anonymous inner class as method argument.
interface HelloWorld
{
   String print();
}
public class AnonymousInnerDemo
{
   // method accepts object of interface HelloWorld
   public void display(HelloWorld m)
   {
      System.out.println(m.print() + "example of anonymous inner class as method argument.");
   }
   public static void main(String[] args)
   {
      AnonymousInnerDemo obj = new AnonymousInnerDemo();
      // pass an anonymous inner class as an argument
      obj.display(new HelloWorld() {
         public String print() {
            return "Hi! ";
         }
      });
   }
}

Example 2: Nested classes in java

// how to access private members of a class.
class OuterClass
{
   // outer class private variable
   private int number = 56;
   // inner class
   public class InnerClass
   {
      public int showNumber()
      {
         System.out.println("showNumber() method of inner class.");
         return number;
      }
   }
}
public class AccessPrivateMembers
{
   public static void main(String[] args)
   {
      OuterClass objOuter = new OuterClass();
      OuterClass.InnerClass objInner = objOuter.new InnerClass();
      System.out.println(objInner.showNumber());
   }
}