Question

How is this method coded in Java?

Answer 1

First of all, let's see what the this() method is:
this(); is a constructor which is used to call another constructor in a class.

this() can have many uses. Some of them are as follows:

1. this can be passed as an argument in the method call.
2. this can be passed as an argument in the constructor call.
3. this can be used to return the current class instance from the method.
4. this can be used to refer current class instance variable.
5. this can be used to implicitly invoke a current class method

Please refer to the comments of the program for more clarity and to understand how this method is coded.

class Solution{
  public Solution(int,int)
   { this(10, 20); // Here this will call default constructor
          // Logic goes here
   }
 public Solution()
   {
     //code
   }
 public Solution(float,float)
   { this(); // Here this will call default type constructor
     // Logic goes here
   }
}

So, as we can see this() method is nothing but a method which is ready-made for us to use. Implementation wise it is as similar to a normal method.
Note: These things can be a little intimidating in the beginning. But analysing it, again and again, will make it simpler.

Please let me know in the comments in case of any confusion. Also, please upvote if you like.