why write nested classes in java code example

Example 1: Nested classes in java

// example on static nested classes java
import java.util.*;
public class OuterClass
{
   static class NestedClass
   {
      public void display() 
      {
         System.out.println("static nested class example");
      }
   }
   public static void main(String[] args) 
   {
      OuterClass.NestedClass nested = new OuterClass.NestedClass();	 
      nested.display();
   }
}

Example 2: use of nested class in java

In Java, it is possible to define a class within another class, such 
classes are known as nested classes. They enable you to logically group 
classes that are only used in one place, thus this increases the use of 
encapsulation, and creates more readable and maintainable code.