If user inputs random letter, how do I change all of that letter in a given string?

Question

I am trying to figure out how to use character wrapping to mutate a string based on user input. If string is \'Bob loves to build building\' and user enters \'b\' I have to mak

Answer 1

A simplistic approach would be:

String phrase = "I want to replace letters in this phase";
phrase = phrase.replace(letter.toLowerCase(), exchange);
phrase = phrase.replace(letter.toUpperCase(), exchange);

EDIT: Added toLowerCase() as per suggestion below.