Can aybody know How it is working? Here Join method is related to Strings or multithreading?

Question

https://code.sololearn.com/cA54FGi8vPr6/?ref=app

Answer 1

It belongs to the String class and has nothing to do with threads.

The String.join() takes a delimiter as the first argument and followed by a series of character sequences.

Try printing this.
String c = String.join(" and ",a,b);

In your code you need one more argument passed to join() to see the effect of 'a'.

Answer 2

Thanks Avinesh
Now i know the whole concept☺🙂