public class StringFormatter {
 
  public static String reverse(String string_in) {
    if (string_in.trim().length() == 0) { // bug 1 - reverse(" ") returns ""
      return "";
    }
    StringBuffer sb = new StringBuffer(string_in);
    return sb.reverse().toString();
  }
  
  public static int size(String string_in) {
    if (string_in.length() == 0) {  // bug 2 - "".length() returns 1
      return 1;
    }
    return string_in.length();
  }
  
  public static String upcase(String string_in) {
    string_in += ".";  // bug 3 - append a period
    return string_in.toUpperCase();
  }
  
  public static String downcase(String string_in) {
    return string_in.toLowerCase(); // no bugs
  }
  
}