Java Find the difference between two dates

September 17, 2018

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Java Find the difference between two dates

In Java, twoDate DifferenceHere is a sample program to find
The sample program supports the case where the date to be compared is a string ( yyyy/MM/dd ), java.util.

Date DifferenceThe following is the calculation method for determining

The first two dates are converted to long values.
This long value is the number of milliseconds elapsed since January 1, 1970 00:00:00 GMT.
Next, find the difference.
The difference in dates can be obtained by dividing the quantity from the above calculation by the hours of the day.
One day (24 hours) is 86,400,000 milliseconds.

sample source

/** * 2つの日付の差を求めます。 * 日付文字列 strDate1 – strDate2 が何日かを返します。 * * @param strDate1 日付文字列 yyyy/MM/dd * @param strDate2 日付文字列 yyyy/MM/dd * @return 2つの日付の差 * @throws ParseException 日付フォーマットが不正な場合 */ public static int differenceDays(String strDate1,String strDate2) throws ParseException { Date date1 = DateFormat.getDateInstance().parse(strDate1); Date date2 = DateFormat.getDateInstance().parse(strDate2); return differenceDays(date1,date2); } /** * 2つの日付の差を求めます。 * java.util.Date 型の日付 date1 – date2 が何日かを返します。 * * 計算方法は以下となります。 * 1.最初に2つの日付を long 値に変換します。 * 　※この long 値は 1970 年 1 月 1 日 00:00:00 GMT からの * 　経過ミリ秒数となります。 * 2.次にその差を求めます。 * 3.上記の計算で出た数量を 1 日の時間で割ることで * 　日付の差を求めることができます。 * 　※1 日 ( 24 時間) は、86,400,000 ミリ秒です。 * * @param date1 日付 java.util.Date * @param date2 日付 java.util.Date * @return 2つの日付の差 */ public static int differenceDays(Date date1,Date date2) { long datetime1 = date1.getTime(); long datetime2 = date2.getTime(); long one_date_time = 1000 * 60 * 60 * 24; long diffDays = (datetime1 – datetime2) / one_date_time; return (int)diffDays; }

execution (e.g. program)

◆Example of Execution

public static void main(String[] args) {
    int ret = differenceDays("2008/6/2", "2008/6/1");
    System.out.println("result 1 = "+ret);

    ret = differenceDays("2008/6/1", "2008/6/3");
    System.out.println("result 2 = "+ret);

    // May has 31 days
    ret = differenceDays("2008/6/1", "2008/5/1");
    System.out.println("result 3 = "+ret);

    // 30 days in June
    ret = differenceDays("2008/7/1", "2008/6/1");
    System.out.println("result 4 = "+ret);

    // 2008 is a leap year, so the end date of February is the 29th day of the month
    ret = differenceDays("2008/3/1", "2008/2/2/28");
    System.out.println("result 5 = "+ret);");
}

◆Execution Result

Result 1 = 1
Result 2 = -2
Result 3 = 31
Result 4 = 30
Result 5 = 2

Finding the difference between two dates is relatively easy, but finding the difference in months is a bit more challenging. Please see below for reference.
."Java Find the difference between the number of months between two dates"

This sample program is a Chat&Messenger "Calendar and scheduling functionsThe actual use of the system is done in the "I'm a fan of this system.

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