How to compare LocalDate instances Java 8

问题

I am writing an app that needs to be quite accurate in dates and I wonder how can I compare LocalDate instances.. for now I was using something like:

LocalDate localdate1 = LocalDate().now();
LocalDate localdate2 = someService.getSomeDate();
localdate1.equals(localdate2);

But I noticed that my app is giving me some confusing results, and I think it is because of the date comparing.

I am thinking about obtaining the time from 1970' in long and compare those two, but I must be easier, I am sure of it

回答1:

Using equals() LocalDate does override equals:

int compareTo0(LocalDate otherDate) {
    int cmp = (year - otherDate.year);
    if (cmp == 0) {
        cmp = (month - otherDate.month);
        if (cmp == 0) {
            cmp = (day - otherDate.day);
        }
    }
    return cmp;
}

If you are not happy with the result of equals(), you are good using the predefined methods of LocalDate.

isAfter()
isBefore()
isEqual()

Notice that all of those method are using the compareTo0() method and just check the cmp value. if you are still getting weird result (which you shouldn't), please attach an example of input and output

回答2:

LocalDate ld ....;
LocalDateTime ldtime ...;

ld.isEqual(LocalDate.from(ldtime));

回答3:

I believe this snippet will also be helpful in a situation where the dates comparison spans more than two entries.

static final int COMPARE_EARLIEST = 0;

static final int COMPARE_MOST_RECENT = 1;


public LocalDate getTargetDate(List<LocalDate> datesList, int comparatorType) { 
   LocalDate refDate = null;
   switch(comparatorType)
   {
       case COMPARE_EARLIEST:         
       //returns the most earliest of the date entries
          refDate = (LocalDate) datesList.stream().min(Comparator.comparing(item -> 
                      item.toDateTimeAtCurrentTime())).get();
          break;

       case COMPARE_MOST_RECENT:
          //returns the most recent of the date entries 
          refDate = (LocalDate) datesList.stream().max(Comparator.comparing(item -> 
                    item.toDateTimeAtCurrentTime())).get();
          break;
   }

   return refDate;
}

来源：https://stackoverflow.com/questions/29201103/how-to-compare-localdate-instances-java-8

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date

compare

java-8