Is a string immutable?if yes then how to make it mutable?

Answer 1

I was about to tell you to read about mutable and immutable strings in your other post but since you have asked for it now I would like you to take a good look at this example.
https://code.sololearn.com/cSxvqwkmm0zm/?ref=app

Answer 2

Yes. Simply if you want mutable version of strings use StringBuffer, StringBuilder classes...
Please follow what ~swim~ said...