@@ -0,0 +1,200 @@
+public String doubleChar(String str) %7B%0A  String out = %22%22;%0A  for (int i=0; i%3Cstr.length(); i++) %7B%0A    String letter = Character.toString(str.charAt(i));%0A    out += letter + letter;%0A  %7D%0A  return out;%0A%7D%0A

Create doubleChar.java