@@ -0,0 +1,192 @@
+public String changeXY(String str) %7B%0A  if (str.length() == 0) return %22%22;%0A  if (str.charAt(0) == 'x') str = %22y%22 + str.substring(1);%0A  return str.substring(0, 1) + changeXY(str.substring(1));%0A%7D%0A

Create changeXY.java