"this" Keyword in Java

public class ThisKeywordDemo {

     int a;

     int b;

     /**

      * This main method is written to test our demo
      *
      * @param args      */
    public static void main(String[] args) {
          // Declaring a object "result" to store sum of two objects.
         ThisKeywordDemo result = new ThisKeywordDemo();

         // Declaring and Initializing obj1

        ThisKeywordDemo obj1 = new ThisKeywordDemo();
        obj1.a = 5;
       obj1.b = 2;

        // Declaring and Initializing obj2

       ThisKeywordDemo obj2 = new ThisKeywordDemo();
       obj2.a = 3;

       obj2.b = 4;

       /*  == First Call of add method ==

        * Calling add method to add obj1 and obj2
        * Where "obj1" will be accessed by "this" keyword and "obj2" is passed as parameter
        */

        result = obj1.add(obj2);

       System.out.println("=========== Sum of Obj1 and Obj2 ===========");

       System.out.println("Result : a = " + result.a + " b : " + result.b);       
      // Declaring and Initializing obj3
      ThisKeywordDemo obj3 = new ThisKeywordDemo();

      obj3.a = 25;
      obj3.b = 21;

    
     /* == Second Call of add method ==
      * Calling add method to add obj1 and obj3
      * Where "obj3" will be accessed by "this" keyword and "obj2" is passed as parameter
      * -- Here parameter is same in both calls of add method..

      * only invoking object is changed,which will be accessed by "this" Keyword.

      */

      result = obj3.add(obj2);

      System.out.println("================ Sum of Obj2 and Obj3 ===========");

      System.out.println("Result : a = " + result.a + " b : " + result.b);

}

/*

* This method is used to add two objects of ThisKeywordDemo class.
* e.g
* Input:

*          obj1 => obj1.a = 5, obj1.b= 2

*          obj2 => obj2.a = 3, obj2.b= 4

* Output:

*          obj3 => obj3.a = 8, obj3.b = 6

*/

     public ThisKeywordDemo add(ThisKeywordDemo thisKeywordDemo) {

          ThisKeywordDemo temp = new ThisKeywordDemo();

          temp.a = this.a + thisKeywordDemo.a;

          temp.b = this.b + thisKeywordDemo.b;          return temp;
     }

}