public class Zeichen {
  public static String umwandlung(String s) {
    String r = "";
    int z = 0;
    while (z < s.length()) {
      char c = s.charAt(z);
      if (Character.isLowerCase(c)) {
        r += Character.toUpperCase(c);
      }
      else {
        //if (Character.isUpperCase(c)) \{
          r += Character.toLowerCase(c);
        //\}
      }
      ++z;
    }
    return r;
  }
}