如何使用 SimpleDateFormat 仅解析日期

发布于 2024-12-13 05:23:29 字数 516 浏览 3 评论 0原文

我想解析用户给定的日期，但具有特定的格式：一周的日期名称。

到目前为止，这就是我所做的：

SimpleDateFormat format = new SimpleDateFormat("E", Locale.ENGLISH);

try {
    Date date = format.parse ("Friday");
    Calendar calendar = format.getCalendar();
    calendar.add(Calendar.WEEK_OF_YEAR, 1);
    return calendar.getTime();
}
catch (ParseException pe) {
    return null;
}

但这返回了我：

2 janv. 1970 00:00:00

我希望它返回我未来的星期五（在我们的游戏中时光倒流中，2011 年 11 月 4 日）

我该怎么办？

原文

I'd like to parse given date by user but with a specific format : the day name of the week.

So far, here's what I did :

SimpleDateFormat format = new SimpleDateFormat("E", Locale.ENGLISH);

try {
    Date date = format.parse ("Friday");
    Calendar calendar = format.getCalendar();
    calendar.add(Calendar.WEEK_OF_YEAR, 1);
    return calendar.getTime();
}
catch (ParseException pe) {
    return null;
}

But this returns me :

2 janv. 1970 00:00:00

I'd like it to return me the future friday (in our timelapse, 4 nov. 2011)

How can I do ?

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谈下烟灰 2024-12-20 05:23:29

仅解析日期，将其放入 Calendar 中，以便您可以找到星期几，然后根据当前日期创建另一个日历，以便您可以设置星期几：

currentCalendar.set(Calendar.DAY_OF_WEEK,
                    parsedCalendar.get(Calendar.DAY_OF_WEEK));

请注意，这不一定会将其置于未来 - 它将设置当前周内的日期。因此，如果您想确保它确实是在未来，您可能需要在之后添加一周：（

// Assume we've already done all the parsing
int dayOfWeek = parsedCalendar.get(Calendar.DAY_OF_WEEK);

long now = System.currentTimeMillis();
Calendar currentCalendar = Calendar.getInstance();
currentCalendar.setTimeInMillis(now);
currentCalendar.set(Calendar.DAY_OF_WEEK, dayOfWeek);
if (currentCalendar.getTimeInMillis() < now) {
    currentCalendar.add(Calendar.DAY_OF_MONTH, 7);
}

如果当前星期几与解析的星期几相同，您应该检查您想要什么行为......

），我个人建议使用 Joda Time 来处理 Java 中所有重要的日期和时间工作。这是一个更好的 API。

Parse just the day, put that into a Calendar so that you can find the day of the week, then create another calendar based on the current date so that you can set the day of week:

currentCalendar.set(Calendar.DAY_OF_WEEK,
                    parsedCalendar.get(Calendar.DAY_OF_WEEK));

Note that that won't necessarily put it into the future - it'll set the day within the current week. So you may want to add a week afterwards, if you want to ensure that it's really in the future:

// Assume we've already done all the parsing
int dayOfWeek = parsedCalendar.get(Calendar.DAY_OF_WEEK);

long now = System.currentTimeMillis();
Calendar currentCalendar = Calendar.getInstance();
currentCalendar.setTimeInMillis(now);
currentCalendar.set(Calendar.DAY_OF_WEEK, dayOfWeek);
if (currentCalendar.getTimeInMillis() < now) {
    currentCalendar.add(Calendar.DAY_OF_MONTH, 7);
}

(You should check what behaviour you want if the current day of week is the same as the parsed one...)

As an aside, I'd personally recommend using Joda Time for all serious date and time work in Java. It's a much nicer API.

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