java - 使用 Java Calendar (Android) 确定给定字符串时间是否过去

Question

这个问题已经有答案了:

How to compare dates in Java? [duplicate] (11 个回答)

已关闭 5 年前。

我正在尝试编写“isPast(String dateStr)”函数，该函数接收日期字符串，如果是过去的则返回 true，否则返回 false。

private static boolean isPast(String dateStr) {
    Calendar c = GregorianCalendar.getInstance();

    int currentYear = c.get(Calendar.YEAR);
    int currentMonth = c.get(Calendar.MONTH);
    int currentDay = c.get(Calendar.DAY_OF_MONTH);
    int currentHour = c.get(Calendar.HOUR_OF_DAY);
    int currentMinute = c.get(Calendar.MINUTE);
    c.set(currentYear, currentMonth, currentDay, currentHour, currentMinute);
    Date now = c.getTime();

    SimpleDateFormat sdfDates = new SimpleDateFormat("dd/m/yyyy");

    Date date = null;
    try {
        date = sdfDates.parse(dateStr);

    } catch (ParseException e) {
        e.printStackTrace();
    }

    if (now.compareTo(date) == 1){
        System.out.println(dateStr + " date given is past");
        return true;
    }
    System.out.println(dateStr + " date given is future");
    return false;
}

我用以下方式调用它:

 String str1 = "22/04/2018";
 String str2 = "22/01/2018";
 System.out.println(isPast(str1));
 System.out.println(isPast(str2));

输出是:

22/04/2018 date given is past
22/01/2018 date given is past

这是怎么回事？这不是真的。我在这个问题上花了太长时间 - 它应该很简单，显然我错过了日历对象的一些东西......

Answer 1

使用 Java 8 中提供的 LocalDate

  public static void main(String[] args) {

    String str1 = "22/04/2018";
    String str2 = "22/01/2018";
    System.out.println(isPast(str1));
    System.out.println(isPast(str2));
  }


  private static boolean isPast(String dateStr) {

    DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
    LocalDate dates = LocalDate.parse(dateStr, formatter);

    return dates.isBefore(LocalDate.now());
  }