Calculating days between two dates with Java

UPDATE

The original answer from 2013 is now outdated because some of the classes have been replaced. The new way of doing this is using the new java.time classes.

24-hour days

DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd MM yyyy");
String inputString1 = "23 01 1997";
String inputString2 = "27 04 1997";

try {
    LocalDateTime date1 = LocalDate.parse(inputString1, dtf);
    LocalDateTime date2 = LocalDate.parse(inputString2, dtf);
    long daysBetween = Duration.between(date1, date2).toDays();
    System.out.println ("Days: " + daysBetween);
} catch (ParseException e) {
    e.printStackTrace();
}

Calendar days

Note that the solution above counts days as generic chunks of 24 hours, not calendar days.

For calendar days, use java.time.temporal.ChronoUnit.DAYS and its between method.

long daysBetween = ChronoUnit.DAYS.between(date1, date2) ;

Original answer (outdated as of Java 8)

You are making some conversions with your Strings that are not necessary. There is a SimpleDateFormat class for it - try this:

SimpleDateFormat myFormat = new SimpleDateFormat("dd MM yyyy");
String inputString1 = "23 01 1997";
String inputString2 = "27 04 1997";

try {
    Date date1 = myFormat.parse(inputString1);
    Date date2 = myFormat.parse(inputString2);
    long diff = date2.getTime() - date1.getTime();
    System.out.println ("Days: " + TimeUnit.DAYS.convert(diff, TimeUnit.MILLISECONDS));
} catch (ParseException e) {
    e.printStackTrace();
}

EDIT

Since there have been some discussions regarding the correctness of this code: it does indeed take care of leap years. However, the TimeUnit.DAYS.convert function loses precision since milliseconds are converted to days (see the linked doc for more info). If this is a problem, diff can also be converted by hand:

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

Note that this is a float value, not necessarily an int.

Simplest way:

public static long getDifferenceDays(Date d1, Date d2) {
    long diff = d2.getTime() - d1.getTime();
    return TimeUnit.DAYS.convert(diff, TimeUnit.MILLISECONDS);
}

In Java 8, you could accomplish this by using LocalDate and DateTimeFormatter. From the Javadoc of LocalDate:

LocalDate is an immutable date-time object that represents a date, often viewed as year-month-day.

And the pattern can be constructed using DateTimeFormatter. Here is the Javadoc, and the relevant pattern characters I used:

Symbol - Meaning - Presentation - Examples

y - year-of-era - year - 2004; 04

M/L - month-of-year - number/text - 7; 07; Jul; July; J

d - day-of-month - number - 10

Here is the example:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;

public class Java8DateExample {
    public static void main(String[] args) throws IOException {
        final DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd MM yyyy");
        final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        final String firstInput = reader.readLine();
        final String secondInput = reader.readLine();
        final LocalDate firstDate = LocalDate.parse(firstInput, formatter);
        final LocalDate secondDate = LocalDate.parse(secondInput, formatter);
        final long days = ChronoUnit.DAYS.between(firstDate, secondDate);
        System.out.println("Days between: " + days);
    }
}

Example input/output with more recent last:

23 01 1997
27 04 1997
Days between: 94

With more recent first:

27 04 1997
23 01 1997
Days between: -94

Well, you could do it as a method in a simpler way:

public static long betweenDates(Date firstDate, Date secondDate) throws IOException
{
    return ChronoUnit.DAYS.between(firstDate.toInstant(), secondDate.toInstant());
}

Most / all answers caused issues for us when daylight savings time came around. Here's our working solution for all dates, without using JodaTime. It utilizes calendar objects:

public static int daysBetween(Calendar day1, Calendar day2){
    Calendar dayOne = (Calendar) day1.clone(),
            dayTwo = (Calendar) day2.clone();

    if (dayOne.get(Calendar.YEAR) == dayTwo.get(Calendar.YEAR)) {
        return Math.abs(dayOne.get(Calendar.DAY_OF_YEAR) - dayTwo.get(Calendar.DAY_OF_YEAR));
    } else {
        if (dayTwo.get(Calendar.YEAR) > dayOne.get(Calendar.YEAR)) {
            //swap them
            Calendar temp = dayOne;
            dayOne = dayTwo;
            dayTwo = temp;
        }
        int extraDays = 0;

        int dayOneOriginalYearDays = dayOne.get(Calendar.DAY_OF_YEAR);

        while (dayOne.get(Calendar.YEAR) > dayTwo.get(Calendar.YEAR)) {
            dayOne.add(Calendar.YEAR, -1);
            // getActualMaximum() important for leap years
            extraDays += dayOne.getActualMaximum(Calendar.DAY_OF_YEAR);
        }

        return extraDays - dayTwo.get(Calendar.DAY_OF_YEAR) + dayOneOriginalYearDays ;
    }
}

The best way, and it converts to a String as bonus ;)

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    try {
        //Dates to compare
        String CurrentDate=  "09/24/2015";
        String FinalDate=  "09/26/2015";

        Date date1;
        Date date2;

        SimpleDateFormat dates = new SimpleDateFormat("MM/dd/yyyy");

        //Setting dates
        date1 = dates.parse(CurrentDate);
        date2 = dates.parse(FinalDate);

        //Comparing dates
        long difference = Math.abs(date1.getTime() - date2.getTime());
        long differenceDates = difference / (24 * 60 * 60 * 1000);

        //Convert long to String
        String dayDifference = Long.toString(differenceDates);

        Log.e("HERE","HERE: " + dayDifference);
    }
    catch (Exception exception) {
        Log.e("DIDN'T WORK", "exception " + exception);
    }
}

Use:

public int getDifferenceDays(Date d1, Date d2) {
    int daysdiff = 0;
    long diff = d2.getTime() - d1.getTime();
    long diffDays = diff / (24 * 60 * 60 * 1000) + 1;
    daysdiff = (int) diffDays;
    return daysdiff;
}

Java date libraries are notoriously broken. I would advise to use Joda Time. It will take care of leap year, time zone and so on for you.

Minimal working example:

import java.util.Scanner;
import org.joda.time.DateTime;
import org.joda.time.Days;
import org.joda.time.LocalDate;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

public class DateTestCase {

    public static void main(String[] args) {

        System.out.print("Insert first date: ");
        Scanner s = new Scanner(System.in);
        String firstdate = s.nextLine();
        System.out.print("Insert second date: ");
        String seconddate = s.nextLine();

        // Formatter
        DateTimeFormatter dateStringFormat = DateTimeFormat
                .forPattern("dd MM yyyy");
        DateTime firstTime = dateStringFormat.parseDateTime(firstdate);
        DateTime secondTime = dateStringFormat.parseDateTime(seconddate);
        int days = Days.daysBetween(new LocalDate(firstTime),
                                    new LocalDate(secondTime)).getDays();
        System.out.println("Days between the two dates " + days);
    }
}

If you want to get just days(no times), then you can use ChronoUnit

ChronoUnit.DAYS.between(date1.toLocalDate(), date2.toLocalDate());

String dateStart = "01/14/2015 08:29:58";
String dateStop = "01/15/2015 11:31:48";

//HH converts hour in 24 hours format (0-23), day calculation
SimpleDateFormat format = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss");

Date d1 = null;
Date d2 = null;

d1 = format.parse(dateStart);
d2 = format.parse(dateStop);

//in milliseconds
long diff = d2.getTime() - d1.getTime();

long diffSeconds = diff / 1000 % 60;
long diffMinutes = diff / (60 * 1000) % 60;
long diffHours = diff / (60 * 60 * 1000) % 24;
long diffDays = diff / (24 * 60 * 60 * 1000);

System.out.print(diffDays + " days, ");
System.out.print(diffHours + " hours, ");
System.out.print(diffMinutes + " minutes, ");
System.out.print(diffSeconds + " seconds.");

We can make use of LocalDate and ChronoUnit java library, Below code is working fine. Date should be in format yyyy-MM-dd.

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;
import java.util.*;
class Solution {
    public int daysBetweenDates(String date1, String date2) {
        LocalDate dt1 = LocalDate.parse(date1);
        LocalDate dt2= LocalDate.parse(date2);

        long diffDays = ChronoUnit.DAYS.between(dt1, dt2);

        return Math.abs((int)diffDays);
    }
}

When I run your program, it doesn't even get me to the point where I can enter the second date.

This is simpler and less error prone.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Test001 {

    public static void main(String[] args) throws Exception {

        BufferedReader br = null;

        br = new BufferedReader(new InputStreamReader(System.in));
        SimpleDateFormat sdf = new SimpleDateFormat("dd MM yyyy");

        System.out.println("Insert first date : ");
        Date dt1 = sdf.parse(br.readLine().trim());

        System.out.println("Insert second date : ");
        Date dt2 = sdf.parse(br.readLine().trim());

        long diff = dt2.getTime() - dt1.getTime();

        System.out.println("Days: " + diff / 1000L / 60L / 60L / 24L);

        if (br != null) {
            br.close();
        }
    }
}

// date format, it will be like "2015-01-01"
private static final String DATE_FORMAT = "yyyy-MM-dd";

// convert a string to java.util.Date
public static Date convertStringToJavaDate(String date)
        throws ParseException {
    DateFormat dataFormat = new SimpleDateFormat(DATE_FORMAT);
    return dataFormat.parse(date);
}

// plus days to a date
public static Date plusJavaDays(Date date, int days) {
    // convert to jata-time
    DateTime fromDate = new DateTime(date);
    DateTime toDate = fromDate.plusDays(days);
    // convert back to java.util.Date
    return toDate.toDate();
}

// return a list of dates between the fromDate and toDate
public static List<Date> getDatesBetween(Date fromDate, Date toDate) {
    List<Date> dates = new ArrayList<Date>(0);
    Date date = fromDate;
    while (date.before(toDate) || date.equals(toDate)) {
        dates.add(date);
        date = plusJavaDays(date, 1);
    }
    return dates;
}

The following works perfectly well for me:

public int daysBetween(LocalDate later, LocalDate before) {
        SimpleDateFormat myFormat = new SimpleDateFormat("dd MM yyyy");
        int daysBetween = 0;
        try {
            Date dateBefore = myFormat.parse(localDateToString(before));
            Date dateAfter = myFormat.parse(localDateToString(later));
            long difference = dateAfter.getTime() - dateBefore.getTime();
            daysBetween = (int) (difference / (1000 * 60 * 60 * 24));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return daysBetween;
    }

    public String localDateToString(LocalDate date) {
        DateTimeFormatter myFormat = DateTimeFormatter.ofPattern("dd MM yyyy");
        return date.format(myFormat).toString();
    }

All the other answers had lots of scary things, here's my simple solution:

public int getDaysDiff(Date dateToCheck) 
{
    long diffMilliseconds = new Date().getTime() - dateToCheck.getTime();
    double diffSeconds = diffMilliseconds / 1000;
    double diffMinutes = diffSeconds / 60;
    double diffHours = diffMinutes / 60;
    double diffDays = diffHours / 24;
        
    return (int) Math.round(diffDays);
}

public class TestCode {

    public static void main(String[] args) {        
        String date1 = "23-04-2021";
        String date2 = "24-05-2021";
        System.out.println("NDays: " + nDays_Between_Dates(date1, date2));      
    }
    
    public static int nDays_Between_Dates(String date1, String date2) {
        int diffDays = 0;
        try {
            SimpleDateFormat dates = new SimpleDateFormat("dd-MM-yyyy");
            Date startDate = dates.parse(date1);
            Date endDate = dates.parse(date2);
            long diff = endDate.getTime() - startDate.getTime();
            diffDays = (int) (diff / (24 * 60 * 60 * 1000));            
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return Math.abs(diffDays);
    }
}

Output: NDays: 31

Use following to covert the timestamp from sql Timestamp values and calculate the date differances.

        SimpleDateFormat dates = new SimpleDateFormat("MM/dd/yyyy");

        //Setting dates
        Date ExDate = dates.parse(dates.format(Timestamp.valueOf(ex_date)));
        Date today = dates.parse(dates.format(new Timestamp(System.currentTimeMillis())));

        //Comparing dates
        long differenceDates = Math.abs(ExDate.getTime() - today.getTime()) / (24 * 60 * 60 * 1000);

        //Convert long to String
        String dayDifference = Long.toString(differenceDates); 
        System.out.println(dayDifference);

Since just the dates are given, without considering the time, we can use ChronoUnit class,

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.util.Scanner;

class Demo
{
    public static void main(String args[])
    {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd MM yyyy");

        Scanner sc = new Scanner(System.in);
        String s1 = sc.nextLine();
        String s2 = sc.nextLine();

        LocalDate dateBefore = LocalDate.parse(s1, dtf);
        LocalDate dateAfter = LocalDate.parse(s2, dtf);

        System.out.println(ChronoUnit.DAYS.between(dateBefore, dateAfter));
    }
}

public static String dateCalculation(String getTime, String dependTime) {
    //Time A is getTime that need to calculate.
    //Time B is static time that Time A depend on B Time and calculate the result.

    Date date = new Date();
    final SimpleDateFormat sdf = new SimpleDateFormat("yyy-MM-dd H:mm:ss");
    Date dateObj = null;
    Date checkDate = null;

    try {
        dateObj = sdf.parse(getTime);
    } catch (ParseException e) {
        e.printStackTrace();
        return "0";
    }
    SimpleDateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");

    String checkInDate = dateFormat.format(dateObj).toString();
    Date defaultTime = null;
    try {
        defaultTime = dateFormat.parse(dependTime);
        checkDate = dateFormat.parse(checkInDate);
    } catch (ParseException e) {
        e.printStackTrace();
        return "0";
    }

    try {
        if (dateFormat.parse(dateFormat.format(date)).after(defaultTime)) {
            long diff = checkDate.getTime() - defaultTime.getTime();
            Log.e("Difference", "onBindViewHolder: Difference: " + dateObj + " : " + defaultTime + " : " + diff);
            if (diff > 0) {
                long diffSeconds = diff / 1000 % 60;
                long diffMinutes = diff / (60 * 1000) % 60;
                long diffHours = diff / (60 * 60 * 1000);

                return "Late: " + diffHours + " Hour, " + diffMinutes + " Minutes, " + diffSeconds + " Sec";
            } else {
                return "0";
            }
        }
    } catch (ParseException e) {
        e.printStackTrace();
        return "0";
    }
    return "0";
}