如果你只想比较两个没有时间的日期，那么下面的代码可能会帮助你:

final SimpleDateFormat dateFormat = new SimpleDateFormat("yyyyMMdd");
Date dLastUpdateDate = dateFormat.parse(20111116);
Date dCurrentDate = dateFormat.parse(dateFormat.format(new Date()));
if (dCurrentDate.after(dLastUpdateDate))
{
   add your logic
}

// Create one day 00:00:00 calendar
int oneDayTimeStamp = 1523017440;
Calendar oneDayCal = Calendar.getInstance();
oneDayCal.setTimeInMillis(oneDayTimeStamp * 1000L);
oneDayCal.set(Calendar.HOUR_OF_DAY, 0);
oneDayCal.set(Calendar.MINUTE, 0);
oneDayCal.set(Calendar.SECOND, 0);
oneDayCal.set(Calendar.MILLISECOND, 0);

// Create current day 00:00:00 calendar
Calendar currentCal = Calendar.getInstance();
currentCal.set(Calendar.HOUR_OF_DAY, 0);
currentCal.set(Calendar.MINUTE, 0);
currentCal.set(Calendar.SECOND, 0);
currentCal.set(Calendar.MILLISECOND, 0);

if (oneDayCal.compareTo(currentCal) == 0) {
    // Same day (excluding time)
}

public static Date getZeroTimeDate(Date fecha) {
    Date res = fecha;
    Calendar calendar = Calendar.getInstance();

    calendar.setTime( fecha );
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);

    res = calendar.getTime();

    return res;
}

Date currentDate = getZeroTimeDate(new Date());// get current date   

这是解决这个问题最简单的方法。

如果你正在寻找一个简单的解决方案，但你不想从你的项目中更改已弃用的java.util.Date类，你可以将这个方法添加到你的项目中，并继续你的探索:

使用java.util.concurrent.TimeUnit

`

public boolean isSameDay(Date first, Date second) {
    long difference_In_Time = first.getTime() - second.getTime();
        // calculate difference in days
        long difference_In_Days = 
        TimeUnit
              .MILLISECONDS
              .toDays(difference_In_Time);
        if (difference_In_Days == 0) {
            return true;
        }
        return false;
    }

`

像这样实现它:

`

Date first = ...;
Date second = ...;
if (isSameDay(first, second)) {
    // congratulations, they are the same
}
else {
   // heads up champ, they are not the same
}

`

我更倾向于直接使用Joda库而不是java.util.Date，因为Joda区分了日期和时间(参见YearMonthDay和DateTime类)。

然而，如果你确实希望使用java.util.Date，我建议写一个实用方法;如。

public static Date setTimeToMidnight(Date date) {
    Calendar calendar = Calendar.getInstance();

    calendar.setTime( date );
    calendar.set(Calendar.HOUR_OF_DAY, 0);
    calendar.set(Calendar.MINUTE, 0);
    calendar.set(Calendar.SECOND, 0);
    calendar.set(Calendar.MILLISECOND, 0);

    return calendar.getTime();
}

    Date today = new Date();
    Date endDate = new Date();//this
    endDate.setTime(endDate.getTime() - ((endDate.getHours()*60*60*1000) + (endDate.getMinutes()*60*1000) + (endDate.getSeconds()*1000)));
    today.setTime(today.getTime() - ((today.getHours()*60*60*1000) + (today.getMinutes()*60*1000) + (today.getSeconds()*1000)));

    System.out.println(endDate.compareTo(today) <= 0);

我只是将小时/分/秒设置为0，所以时间没有问题，因为现在两个日期的时间都是相同的。现在只需使用compareTo。这个方法帮助找到“if dueDate is today”，其中true表示Yes。