Java：字符串替换以转换时间

Question

我正在尝试将存储在数据库中的时间转换为类型字符串，并以适当的格式打印它。我尝试使用.replaceAll。这导致5：3被替换为05:03，但也将17：3变为0107：03。有没有人对正确的方法有任何建议？

  String moduleStartHour = (c.getString(c.getColumnIndex(database.KEY_MODULESTARTHOUR)));
    String moduleStartMinute = (c.getString(c.getColumnIndex(database.KEY_MODULESTARTMINUTE)));

    String newModuleStartHour= moduleStartHour.replaceAll("0", "00").replaceAll("1", "01").replaceAll("2", "03")
            .replaceAll('4', "04").replaceAll("5", "05").replaceAll("6", "06").replaceAll("7", "07").replaceAll("8", "08")
            .replaceAll("9", "09");
    String newModuleStartMinute= moduleStartMinute.replaceAll("0", "00").replaceAll("1", "01").replaceAll("2", "03")
            .replaceAll("4", "04").replaceAll("5", "05").replaceAll("6", "06").replaceAll("7", "07").replaceAll("8", "08")
            .replaceAll("9", "09");

    StringBuilder sb =new StringBuilder();
    sb.append(newModuleStartHour).append(":").append(newModuleStartMinute);
    String moduleStartTime = sb.toString();

Answer 1

if (moduleStartHour.length() == 1)
  moduleStartHour = "0" + moduleStartHour;

if (moduleStartMinute.length() == 1)
   moduleStartMinute  = "0" + moduleStartMinute;

StringBuilder sb =new StringBuilder();
sb.append(moduleStartHour).append(":").append(moduleStartMinute);
String moduleStartTime = sb.toString();

或者如果我们在整个过程中使用StringBuilder

    StringBuilder sb = new StringBuilder();

    if (moduleStartHour.length() == 1)
        sb.append("0");

    sb.append(moduleStartHour).append(":");

    if (moduleStartMinute.length() == 1)
        sb.append("0");

    sb.append(moduleStartMinute);

    String moduleStartTime = sb.toString();