Android 计算两个日期之间的天数

Question

I have written the following code to find days between two dates

    startDateValue = new Date(startDate);
    endDateValue = new Date(endDate);
    long diff = endDateValue.getTime() - startDateValue.getTime();
    long seconds = diff / 1000;
    long minutes = seconds / 60;
    long hours = minutes / 60;
    long days = (hours / 24) + 1;
    Log.d("days", "" + days);

When start and end date are 2/3/2017 and 3/3/2017 respectively the number of days showing is 29.Though when they are of the same day it is showing 1.(The number of days one takes a leave.So if one takes a single day leave,he has to select same start and end date.So in this case he has taken two days leave).

What am I doing wrong? Thank you for your time.

Note: Please don't use the date constructor. Check the accepted answer below. Use simpledateformat or Joda time. Date constructor is deprecated.

Answer 1

Your code for generating date object:

Date date = new Date("2/3/2017"); //deprecated

You are getting 28 days as answer because according to Date(String) constructor it is thinking day = 3,month = 2 and year = 2017

You can convert String to Date as follows:

String dateStr = "2/3/2017";
SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
Date date = sdf.parse(dateStr);

Use above template to make your Date object. Then use below code for calculating days in between two dates. Hope this clear the thing.

It can de done as follows:

long diff = endDateValue.getTime() - startDateValue.getTime();
System.out.println ("Days: " + TimeUnit.DAYS.convert(diff, TimeUnit.MILLISECONDS));

Please check link

If you use Joda Time it is much more simple:

int days = Days.daysBetween(date1, date2).getDays();

Please check JodaTime

How to use JodaTime in Java Project

Answer 2

Kotlin

Here is the example to calculate days from today to some date:

 val millionSeconds = yourDate.time - Calendar.getInstance().timeInMillis
 leftDays.text = TimeUnit.MILLISECONDS.toDays(millionSeconds).toString() + "days"

If you want to calculate two days, then change:

val millionSeconds = yourDate1.time - yourDate2.time

should work.

Answer 3

public static int getDaysDifference(Date fromDate,Date toDate)
{
if(fromDate==null||toDate==null)
return 0;

return (int)( (toDate.getTime() - fromDate.getTime()) / (1000 * 60 * 60 * 24));
}

Answer 4

Does Android fully support java-8 ? If yes you can simple use ChronoUnit class

LocalDate start = LocalDate.of(2017,2,3);
LocalDate end = LocalDate.of(2017,3,3);

System.out.println(ChronoUnit.DAYS.between(start, end)); // 28

or same thing using formatter

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("M/d/yyyy");
LocalDate start = LocalDate.parse("2/3/2017",formatter);
LocalDate end = LocalDate.parse("3/3/2017",formatter);

System.out.println(ChronoUnit.DAYS.between(start, end)); // 28

Answer 5

What date format do you use? Is it d/M/yyyy or M/d/yyyy ?

d = day, M = month, yyyy = year

(see: https://developer.android.com/reference/java/text/SimpleDateFormat.html )

Then the codes:

public static final String DATE_FORMAT = "d/M/yyyy";  //or use "M/d/yyyy"   

public static long getDaysBetweenDates(String start, String end) {
    SimpleDateFormat dateFormat = new SimpleDateFormat(DATE_FORMAT, Locale.ENGLISH);
    Date startDate, endDate;
    long numberOfDays = 0;
    try {
        startDate = dateFormat.parse(start);
        endDate = dateFormat.parse(end);
        numberOfDays = getUnitBetweenDates(startDate, endDate, TimeUnit.DAYS);
    } catch (ParseException e) {
        e.printStackTrace();
    }
    return numberOfDays;
}

And for getUnitBetweenDates method:

private static long getUnitBetweenDates(Date startDate, Date endDate, TimeUnit unit) {
    long timeDiff = endDate.getTime() - startDate.getTime();
    return unit.convert(timeDiff, TimeUnit.MILLISECONDS);
}

Answer 6

Have look at this code , this is helpful for me ,hope it will help you.

public String get_count_of_days(String Created_date_String, String Expire_date_String) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy", Locale.getDefault());

Date Created_convertedDate = null, Expire_CovertedDate = null, todayWithZeroTime = null;
try {
    Created_convertedDate = dateFormat.parse(Created_date_String);
    Expire_CovertedDate = dateFormat.parse(Expire_date_String);

    Date today = new Date();

    todayWithZeroTime = dateFormat.parse(dateFormat.format(today));
} catch (ParseException e) {
    e.printStackTrace();
}

int c_year = 0, c_month = 0, c_day = 0;

if (Created_convertedDate.after(todayWithZeroTime)) {
    Calendar c_cal = Calendar.getInstance();
    c_cal.setTime(Created_convertedDate);
    c_year = c_cal.get(Calendar.YEAR);
    c_month = c_cal.get(Calendar.MONTH);
    c_day = c_cal.get(Calendar.DAY_OF_MONTH);

} else {
    Calendar c_cal = Calendar.getInstance();
    c_cal.setTime(todayWithZeroTime);
    c_year = c_cal.get(Calendar.YEAR);
    c_month = c_cal.get(Calendar.MONTH);
    c_day = c_cal.get(Calendar.DAY_OF_MONTH);
}


/*Calendar today_cal = Calendar.getInstance();
int today_year = today_cal.get(Calendar.YEAR);
int today = today_cal.get(Calendar.MONTH);
int today_day = today_cal.get(Calendar.DAY_OF_MONTH);
*/

Calendar e_cal = Calendar.getInstance();
e_cal.setTime(Expire_CovertedDate);

int e_year = e_cal.get(Calendar.YEAR);
int e_month = e_cal.get(Calendar.MONTH);
int e_day = e_cal.get(Calendar.DAY_OF_MONTH);

Calendar date1 = Calendar.getInstance();
Calendar date2 = Calendar.getInstance();

date1.clear();
date1.set(c_year, c_month, c_day);
date2.clear();
date2.set(e_year, e_month, e_day);

long diff = date2.getTimeInMillis() - date1.getTimeInMillis();

float dayCount = (float) diff / (24 * 60 * 60 * 1000);

return ("" + (int) dayCount + " Days");

}

Answer 7

Very simple, just use Calendar, create two instances for the two dates, convert to milliseconds, subtract and convert to days (rounded up)... like this, basically:

Calendar startDate = Calendar.getInstance();
startDate.set(mStartYear, mStartMonth, mStartDay);
long startDateMillis = startDate.getTimeInMillis();

Calendar endDate = Calendar.getInstance();
endDate.set(mEndYear, mEndMonth, mEndDay);
long endDateMillis = endDate.getTimeInMillis();

long differenceMillis = endDateMillis - startDateMillis;
int daysDifference = (int) (differenceMillis / (1000 * 60 * 60 * 24));

Answer 8

java.time and ThreeTenABP

If I understand correctly, you want the number of days from start day through end date inclusive .

    DateTimeFormatter dateFormatter = DateTimeFormatter.ofPattern("d/M/u");

    String startDate = "2/3/2017";
    String endDate = "3/3/2017";

    LocalDate startDateValue = LocalDate.parse(startDate, dateFormatter);
    LocalDate endDateValue = LocalDate.parse(endDate, dateFormatter);
    long days = ChronoUnit.DAYS.between(startDateValue, endDateValue) + 1;

    System.out.println("Days: " + days);

Output:

Days: 2

ChronoUnit.DAYS.between() gives us a count of days from start date inclusive to end date exclusive . So to include the end date too we needed to add 1 day just as you did in the question.

What went wrong in your code?

You are using the Date(String) constructor. This constructor has been deprecated since 1997 because it works unreliably across time zones, so don't use it. Also it's kind of magical: at least I never really know what I get. Apparently it takes 2/3/2017 to mean February 3, 2017, where you intended 2 March 2017. From February 3 to March 3 inclusive is 29 days (since 2017 wasn't a leap year). This explains why you got 29. (If necessary, we could spell our way through the documentation and find out why 2/3/2017 is interpreted the way it is, only I'd find that a pointless waste of time to do.)

You can't convert from milliseconds. Please also note that not only the question but also the very many answers that convert from milliseconds to days are incorrect. Such a conversion assumes that a day is always 24 hours. Because of summer time (DST) and other time anomalies a day is not always 24 hours. All of those answers will count a day too few for example if the leave crosses the spring gap or spring forward when summer time begins.

Question: Doesn't java.time require Android API level 26?

java.time works nicely on both older and newer Android devices. It just requires at least Java 6 .

• In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
• In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the modern classes (ThreeTen for JSR 310; see the links at the bottom).
• On (older) Android use the Android edition of ThreeTen Backport. It's called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

Links

• Oracle tutorial: Date Time explaining how to use java.time.
• Java Specification Request (JSR) 310 , where java.time was first described.
• ThreeTen Backport project , the backport of java.time to Java 6 and 7 (ThreeTen for JSR-310).
• ThreeTenABP , Android edition of ThreeTen Backport
• Question: How to use ThreeTenABP in Android Project , with a very thorough explanation.

Answer 9

Be carefur if you'd like to use received integer eg to indicate specific day in custom calendar implementation. For example, I tried to go in m app from monthly calendar view to daily view and show daily content, by calculating dates from 1970-01-01 to selected one, and each 25-31th day of month shows me as one day earlier, because datesDifferenceInMillis / (24 * 60 * 60 * 1000); may return something like 17645,95833333333, and casting this to int you'll get value lower by 1. In this case correctly number of days you'll get by rounding received float by using NumberFormat class. Here's my code:

NumberFormat numberFormat = NumberFormat.getInstance(Locale.getDefault());
numberFormat.setRoundingMode(RoundingMode.HALF_UP);
numberFormat.setMaximumFractionDigits(0);
numberFormat.setMinimumFractionDigits(0);
int days = numberFormat.parse(numberFormat.format(value)).intValue();

I hope it will be helpful.

Answer 10

I modified Jitendra's answer in Kotlin:

fun getDaysBetweenDates(firstDateValue: String, secondDateValue: String, format: String): String
{
    val sdf = SimpleDateFormat(format, Locale.getDefault())

    val firstDate = sdf.parse(firstDateValue)
    val secondDate = sdf.parse(secondDateValue)

    if (firstDate == null || secondDate == null)
        return 0.toString()

    return (((secondDate.time - firstDate.time) / (1000 * 60 * 60 * 24)) + 1).toString()
}

and call it like

val days = getDaysBetweenDates("31-03-2020", "24-04-2020","dd-MM-yyyy")

Answer 11

SUPER SIMPLE

use LocalDate() include implementation 'com.jakewharton.threetenabp:threetenabp:1.2.1' to use in android

Example

IN KOTLIN

val daysDifferene = LocalDate.of(2017,3,3).toEpochDay() - LocalDate.of(2017,3,2)

even better

create extension function to LocalDate class

private operator fun LocalDate.minus(other: LocalDate) = toEpochDay() - other.toEpochDay()
  

now just say

val daysDifference = localDate1 - localDate2 // you get number of days in Long type

IN JAVA

long daysDifference = LocalDate.of(2017,3,3).toEpochDay() - LocalDate.of(2107,3,2) 

Answer 12

You can use joda time, it so simple

fun getBetweenDates(startDate: Long, endDate: Long): String {
    val period = Period(startDate, endDate, PeriodType.yearMonthDayTime())

    val formatter = PeriodFormatterBuilder()
        .appendYears().appendSuffix(" year ")
        .appendMonths().appendSuffix(" month ")
        .appendDays().appendSuffix(" days ")
        .appendHours().appendSuffix(" hours ")
        .appendMinutes().appendSuffix(" minutes ")
        .appendSeconds().appendSuffix(" seconds ")
        .appendMillis().appendSuffix(" millis ")
        .toFormatter()

    return formatter.print(period)
}

start and end dates millisecond, and result example: "2 year 1 month ..."

Answer 13

fun countDaysBetweenTwoCalendar(calendarStart: Calendar, calendarEnd: Calendar) : Int{
    val millionSeconds = calendarEnd.timeInMillis - calendarStart.timeInMillis
    val days = TimeUnit.MILLISECONDS.toDays(millionSeconds) //this way not round number
    val daysRounded = (millionSeconds / (1000.0 * 60 * 60 * 24)).roundToInt()
    return daysRounded
}

Answer 14

while none of these worked for me, here is an easy way to implement your code with a very simple fonction :

private long getDaysDifference(Date fromDate,Date toDate) {

    if(fromDate == null || toDate == null)
        return 0;


    int a = Integer.parseInt(DateFormat.format("dd",   fromDate)+"");
    int b = Integer.parseInt(DateFormat.format("dd",   toDate)+"");

    if ( b <= a){
        return Calendar.getInstance().getActualMaximum(Calendar.DAY_OF_MONTH) + b - a;
    }
    return b - a;
}

EnJoY

Answer 15

use this way :

 fun stringDateToCalendar(dateString: String?, formatString: String): Calendar? {

        if (dateString == null || dateString.isEmpty() || formatString.isBlank())
            return null

        val inputDateFormat = SimpleDateFormat(formatString, Locale.ENGLISH)

        return try {
            inputDateFormat.parse(dateString)?.let {
                val cal = Calendar.getInstance()
                cal.time = it
                cal
            }
        } catch (e: ParseException) {
            null
        }

 }
    
 val calendarFrom = stringDateToCalendar(
      "2021-12-12",
      "yyyy-MM-dd"
 )

 val calendarTo = CalendarUtils.stringDateToCalendar(
      "2022-03-20",
      "yyyy-MM-dd"
 )
    
    

 val msDiff = calendarTo?.timeInMillis?.minus(calendarFrom?.timeInMillis ?: 0) ?: 0
 val daysDiff = TimeUnit.MILLISECONDS.toDays(msDiff)

Answer 16

Here the simply common function Kotlin code

Here comparing these formatted dates "2022-11-04", "2022-11-20" Output will be 16 Days

 open fun dateSubstraction(date1: String, date2: String): String {
        val dateFormatter = SimpleDateFormat("yyyy-MM-dd") //Define input date format here
        val formatedDate1= dateFormat.parse(date1)  //formated  date1
        val formatedDate2= dateFormat.parse(date2)  //formated date2
        val millionSeconds = formatedDate2.time - formatedDate1.time
        return TimeUnit.MILLISECONDS.toDays(millionSeconds).toString()+"Days"
    }

Answer 17

I have done this work in past. This was very simple

 val currentCalendar = Calendar.getInstance()
    val targetCalendar = Calendar.getInstance().apply {
        set(2023, Calendar.APRIL, 9, 23, 59, 59)
    }//your input: date, month, and time
    val difference = targetCalendar.timeInMillis - currentCalendar.timeInMillis
    val differenceInDays = TimeUnit.MILLISECONDS.toDays(difference)
    val remainingMonths = differenceInDays / 30//remaining months
    val remainingDays = differenceInDays % 30//remaining days
    val differenceInSeconds = TimeUnit.MILLISECONDS.toSeconds(difference)
    val differenceInMinutes = TimeUnit.MILLISECONDS.toMinutes(difference)
    val differenceInHours = TimeUnit.MILLISECONDS.toHours(difference)
    val remainingSeconds = differenceInSeconds % 60//remaining seconds
    val remainingMinutes = differenceInMinutes % 60//remaining minutes
    val remainingHours = differenceInHours % 24// remaining hours

Thats It We have done it