/** Update the internal string that represents the display. */
 private void updateDisplay() {
   displayString =
       (hours.getValue() != 0 ? hours.getDisplayValue() : "12")
           + ":"
           + minutes.getDisplayValue()
           + " "
           + (isAm ? "am" : "pm");
 }
 /** Update the internal string that represents the display. */
 private void updateDisplay() {
   displayString = hours.getDisplayValue() + ":" + minutes.getDisplayValue();
 }