Given an input String, return the String after a one-character Caesar cipher where all the input letters are shifted up one letter. Precondition: the input String will have only capital letters in it.

HINT

Use charAt to extract a char at each location. char data can be treated as numbers in many important ways. Remember that to get all the characters in a String, you can use a for loop. Here's an example.

public String apcsaEncryptCaesarString(String str) {
  String out = "";
  for (int i = 0; i < str.length(); i++)
  {
      char c = str.charAt(i);
      // some other stuff happens to c
      // right now we are adding it back in unchanged
      out += c;
  }
  return out;
}