java nested class example

Example 1: Nested classes in java

// example on inner class in java
class OuterDemo
{
   int num;
   // inner class
   private class InnerDemo
   {
      public void display()
      {
         System.out.println("inner class");
      }
   }
   // access inner class from method within
   void printInner()
   {
      InnerDemo objInner = new InnerDemo();
      objInner.display();
   }
}
public class InnerClassExample
{
   public static void main(String[] args)
   {
      OuterDemo objOuter = new OuterDemo();
      objOuter.printInner();
   }
}

Example 2: Nested classes in java

// example on method local inner class in java.
class Outer
{
   // outer class instance method
   void display()
   {
      int num = 96;
      // method-local inner class
      class MethodLocalInner
      {
         public void show()
         {
            System.out.println("in method local inner class " + num);
         }
      } // end of inner class
      // access method local inner class
      MethodLocalInner objInner = new MethodLocalInner();
      objInner.show();
   }
   public static void main(String[] args)
   {
      Outer objOuter = new Outer();
      objOuter.display();
   }
}

Example 3: inner class vs outer class

1. Can Outer class be static? --> No
2. Can inner class be static? --> Yes
3. Can you create an object from the inner class? --> Only if it's static
4. Can we have main method in inner class ? --> Only if it's static
5. Inner class can only be extended if it's static.