title: How to replace all characters in a user input string except one
body: <p>I'm currently in an introductory level Java class, and am working on the classic phrase guess assignment. The object is for one user to enter a secret phrase, and another to guess it one letter at a time. Between guesses, the phrase must be displayed as all question marks except the letters that were guessed correctly. Our class has only really covered some very basic methods, if-else statements and loops up to this point, but I'm trying to research some string methods that may make this a bit easier. </p>
  
  <p>I know of the <code>replace()</code>, <code>replaceAll()</code> and <code>contains()</code> methods, but was wondering if there is a method which allows you to replace all but one character of your choice in a string. </p>
  
  <p>Thanks in advance</p>