Java Find the difference between the number of months between two dates

Java Find the difference between the number of months between two dates

In Java, twoDifference in the number of months of the dateHere 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.

Difference in number of monthsThe following is the calculation method for determining

1. First, the two dates are set to one day.
   Calendar.set(Calendar.DATE, 1).
2. Next, the two dates are compared repeatedly on a month-by-month basis.
   Add or subtract months one month at a time using Calendar.add(Calendar.MONTH, 1 or -1).
3. Counts the number of repeated comparisons.

sample source

/**<br /> * 2つの日付の月数の差を求めます。<br /> * 日付文字列 strDate1 – strDate2 が何ヵ月かを整数で返します。<br /> * ※端数の日数は無視します。<br /> *<br /> * @param strDate1 日付文字列1 yyyy/MM/dd<br /> * @param strDate2 日付文字列2 yyyy/MM/dd<br /> * @return 2つの日付の月数の差<br /> * @throws ParseException 日付フォーマットが不正な場合<br /> */<br /> public static int differenceMonth(String strDate1, String strDate2)<br /> throws ParseException {<br /> Date date1 = DateFormat.getDateInstance().parse(strDate1);<br /> Date date2 = DateFormat.getDateInstance().parse(strDate2);<br /> return differenceMonth(date1,date2);<br /> }<br /> /**<br /> * 2つの日付の月数の差を求めます。<br /> * java.util.Date 型の日付 date1 – date2 が何ヵ月かを整数で返します。<br /> * ※端数の日数は無視します。<br /> *<br /> * @param date1 日付1 java.util.Date<br /> * @param date2 日付2 java.util.Date<br /> * @return 2つの日付の月数の差<br /> */<br /> public static int differenceMonth(Date date1, Date date2) {<br /> Calendar cal1 = Calendar.getInstance();<br /> cal1.setTime(date1);<br /> cal1.set(Calendar.DATE, 1);<br /> Calendar cal2 = Calendar.getInstance();<br /> cal2.setTime(date2);<br /> cal2.set(Calendar.DATE, 1);<br /> int count = 0;<br /> if (cal1.before(cal2)) {<br /> while (cal1.before(cal2)) {<br /> cal1.add(Calendar.MONTH, 1);<br /> count–;<br /> }<br /> } else {<br /> count–;<br /> while (!cal1.before(cal2)) {<br /> cal1.add(Calendar.MONTH, -1);<br /> count++;<br /> }<br /> }<br /> return count;<br /> }<br />

execution (e.g. program)

◆Example of Execution

public static void main(String[] args) {
    int ret = differenceMonth("2008/6/30", "2008/6/1");
    System.out.println("Result 1 = "+ret);

    ret = differenceMonth("2008/7/1", "2008/6/3");
    System.out.println("result 2 = "+ret);

    ret = differenceMonth("2008/12/20", "2008/6/1");
    System.out.println("result 3 = "+ret);

    ret = differenceMonth("2010/6/20", "2008/6/1");
    System.out.println("result 4 = "+ret);

    ret = differenceMonth("2008/6/1", "2008/7/1");
    System.out.println("result 5 = "+ret);

    ret = differenceMonth("2008/7/1", "2009/7/1");
    System.out.println("result 6 = "+ret); ret = differenceMonth("2008/7/1", "2009/7/1"); ret = differenceMonth("2008/7/1", "2009/7/1")
}

◆Execution Result

Result 1 = 0
Result 2 = 1
Result 3 = 6
Result 4 = 24
Result 5 = -1
Result 6 = -12

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