用Java计算两个日期之间的天数

我想要一个Java程序来计算两个日期之间的天数。

输入第一个日期(德语表示法;有空格:"dd mm yyyy") 输入第二个日期。程序应该计算两个日期之间的天数。

我怎样才能把闰年和夏天时包括进来呢?

我的代码:

import java.util.Calendar;
import java.util.Date;
import java.util.Scanner;

public class NewDateDifference {

    public static void main(String[] args) {

        System.out.print("Insert first date: ");
        Scanner s = new Scanner(System.in);
        String[] eingabe1 = new String[3];

        while (s.hasNext()) {
            int i = 0;
            insert1[i] = s.next();
            if (!s.hasNext()) {
                s.close();
                break;
            }
            i++;
        }

        System.out.print("Insert second date: ");
        Scanner t = new Scanner(System.in);
        String[] insert2 = new String[3];

        while (t.hasNext()) {
            int i = 0;
            insert2[i] = t.next();
            if (!t.hasNext()) {
                t.close();
                break;
            }
            i++;
        }

        Calendar cal = Calendar.getInstance();

        cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(insert1[0]));
        cal.set(Calendar.MONTH, Integer.parseInt(insert1[1]));
        cal.set(Calendar.YEAR, Integer.parseInt(insert1[2]));
        Date firstDate = cal.getTime();

        cal.set(Calendar.DAY_OF_MONTH, Integer.parseInt(insert2[0]));
        cal.set(Calendar.MONTH, Integer.parseInt(insert2[1]));
        cal.set(Calendar.YEAR, Integer.parseInt(insert2[2]));
        Date secondDate = cal.getTime();


        long diff = secondDate.getTime() - firstDate.getTime();

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

当前回答

我们可以利用LocalDate和ChronoUnit java库，下面的代码工作正常。 Date的格式为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);
    }
}

2020-03-27 19:18:55

其他回答

我们可以利用LocalDate和ChronoUnit java库，下面的代码工作正常。 Date的格式为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);
    }
}

2020-03-27 19:18:55

Java日期库是出了名的坏。我建议使用Joda Time。它会为你照顾闰年、时区等。

最小工作示例:

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);
    }
}

2013-11-23 18:05:46

当我运行你的程序时，它连我都找不到直到我可以开始第二次约会。

这样更简单，更不容易出错。

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();
        }
    }
}

2013-11-23 17:48:00

最简单的方法:

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

2015-05-12 07:48:43

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);
    }
}

nday: 31天

2021-04-23 06:23:25

用Java计算两个日期之间的天数

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