java 日历逻辑帮助

发布于 2024-10-22 18:24:53 字数 1057 浏览 1 评论 0原文

我正在使用 Java Calendar 类执行以下操作：

设置开始日期
设置结束日期
该范围内的任何日期都是“有效”日期

我对此有些工作，有些则不然。请参阅下面的代码：

    nowCalendar.set(Calendar.DATE, nowCalendar.get(Calendar.DATE) + offset);
    int nowDay = nowCalendar.get(Calendar.DATE);

    Calendar futureCalendar = Calendar.getInstance();
    futureCalendar.set(Calendar.DATE, nowDay + days);

    Date now = nowCalendar.getTime();
    Date endTime = futureCalendar.getTime();

    long now_ms = now.getTime();
    long endTime_ms = endTime.getTime();

    for (; now_ms < endTime_ms; now_ms += MILLIS_IN_DAY) {
        valid_days.addElement(new Date(now_ms));
        System.out.println("VALID DAY: " + new Date(now_ms));
    }

基本上，我设置一个“现在”日历和一个“未来”日历，然后比较两个日历以找到有效日期。在我的日历上，有效日期将显示为白色，无效日期将显示为灰色。您会注意到两个变量：

    offset = three days after the current selected date
    days = the number of valid days from the current selected date

这有效...除非当前选择的日期是该月的最后一天，或两天前（三天在一起）。我认为偏移肯定是把事情搞砸了，但这个逻辑在其他地方都适用。有什么想法吗？

原文

I am working with the Java Calendar class to do the following:

Set a start date
Set an end date
Any date within that range is a "valid" date

I have this somewhat working, and somewhat not. Please see the code below:

    nowCalendar.set(Calendar.DATE, nowCalendar.get(Calendar.DATE) + offset);
    int nowDay = nowCalendar.get(Calendar.DATE);

    Calendar futureCalendar = Calendar.getInstance();
    futureCalendar.set(Calendar.DATE, nowDay + days);

    Date now = nowCalendar.getTime();
    Date endTime = futureCalendar.getTime();

    long now_ms = now.getTime();
    long endTime_ms = endTime.getTime();

    for (; now_ms < endTime_ms; now_ms += MILLIS_IN_DAY) {
        valid_days.addElement(new Date(now_ms));
        System.out.println("VALID DAY: " + new Date(now_ms));
    }

Basically, I set a "NOW" calendar and a "FUTURE" calendar, and then I compare the two calendars to find the valid days. On my calendar, valid days will be shaded white and invalid days will be shaded gray. You will notice two variables:

    offset = three days after the current selected date
    days = the number of valid days from the current selected date

This works...EXCEPT when the current selected date is the last day of the month, or two days prior (three all together). I think that its the offset that is definitely screwing it up, but the logic works everywhere else. Any ideas?

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长安忆 2024-10-29 18:24:53

不要摆弄毫秒。克隆 nowCalendar，在循环中使用 Calendar#add() 添加 1 天，只要不超过 futureCalendar 并获取使用Calendar#getTime()获取日期。

Calendar clone = nowCalendar.clone();

while (!clone.after(futureCalendar)) {
    validDays.add(clone.getTime());
    clone.add(Calendar.DATE, 1);
}

（请注意，我将 validDays 改进为 List，而不是旧版 Vector）

Don't fiddle with milliseconds. Clone the nowCalendar, add 1 day to it using Calendar#add() in a loop as long as it does not exceed futureCalendar and get the Date out of it using Calendar#getTime().

Calendar clone = nowCalendar.clone();

while (!clone.after(futureCalendar)) {
    validDays.add(clone.getTime());
    clone.add(Calendar.DATE, 1);
}

(note that I improved validDays to be a List instead of the legacy Vector)

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德意的啸 2024-10-29 18:24:53

在第一行中使用 add 而不是 set，否则如果您处于月份边界，则不会调整月份：

nowCalendar.add(Calendar.DATE, offset);

Use add instead of set in the first line, otherwise the month is not adjusted if you are at the month boundary:

nowCalendar.add(Calendar.DATE, offset);

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云之铃。 2024-10-29 18:24:53

public boolean isInRange(Date d)
{
   Calendar cal = Calendar.getInstance();
   cal.setTime(d);
   return cal.after(startCal) && cal.before(endCal);
}

这里startCal是开始时间的日历实例，endCal是结束时间。

public boolean isInRange(Date d)
{
   Calendar cal = Calendar.getInstance();
   cal.setTime(d);
   return cal.after(startCal) && cal.before(endCal);
}

Here the startCal is the calendar instance of start time and endCal is end time.

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