Inserting punctuation marks in a java String -

Is there a custom way to insert punctuation in Java string?

Small programs:

  class punctuation {public static zero main (string [] args) {string greeting = "hello how are you"; Println ("Hello"); }}   
 Desired Output: Hello, how are you?   
 
 
 How about:  
  string greetings = "hello" + "," + "How are you";   
 or this:  
  string greetings = "hello how are you"; Best wishes = best wishes. (0, 5) + "," + Good luck. "(5);   
 Or this:  
  string greetings =" hello how are you "; greetings = new stringbilders (greetings) .inet (5 , ","). ToString ();   
 Inserting a punctuation is trivial if you know  where  should go to it but if you already The right place is not known, so it is impossible!