java example of abstraction

Example 1: abstraction in java

Abstraction is nothing but the quality of dealing with ideas rather than 
events. It basically deals with hiding the internal details and showing 
the essential things to the user.

Example 2: Abstraction in java

// example on abstract class in java
import java.util.*;
// abstract class
abstract class Shape
{
   // abstract method
   abstract void sides();
}
class Triangle extends Shape
{
   void sides()
   {
      System.out.println("Triangle shape has three sides.");
   }
}
class Pentagon extends Shape
{
   void sides()
   {
      System.out.println("Pentagon shape has five sides.");
   }
   public static void main(String[] args)
   {
      Triangle obj1 = new Triangle();
      obj1.sides();
      Pentagon obj2 = new Pentagon();
      obj2.sides();
   }
}