Java Calendar Time elapsedTime(Calendar before, Calendar after)

Description

Calculate the total of elapsed time from years up to seconds between the two given calendars.

License

Apache License

Parameter

Parameter	Description
before	The first calendar with expected date before the second calendar.
after	The second calendar with expected date after the first calendar.

Exception

Parameter	Description
IllegalArgumentException	If the first calendar is dated after the second calendar.

Return

The elapsed time between the two given calendars in years, months, days, hours, minutes and seconds.

Declaration

public static int[] elapsedTime(Calendar before, Calendar after)

Method Source Code


//package com.java2s;
//License from project: Apache License 

import java.util.Calendar;

public class Main {
    /**//from  w w  w  .  java 2  s . co m
     * Calculate the total of elapsed time from years up to seconds between the two given calendars.
     * It returns an int array with the elapsed years, months, days, hours, minutes and seconds
     * respectively.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The elapsed time between the two given calendars in years, months, days, hours,
     * minutes and seconds.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int[] elapsedTime(Calendar before, Calendar after) {
        int[] elapsedTime = new int[6];
        Calendar clone = (Calendar) before.clone(); // Otherwise changes are been reflected.

        elapsedTime[0] = elapsedYears(clone, after);
        addYears(clone, elapsedTime[0]);

        elapsedTime[1] = elapsedMonths(clone, after);
        addMonths(clone, elapsedTime[1]);

        elapsedTime[2] = elapsedDays(clone, after);
        addDays(clone, elapsedTime[2]);

        elapsedTime[3] = elapsedHours(clone, after);
        addHours(clone, elapsedTime[3]);

        elapsedTime[4] = elapsedMinutes(clone, after);
        addMinutes(clone, elapsedTime[4]);

        elapsedTime[5] = elapsedSeconds(clone, after);

        return elapsedTime;
    }

    /**
     * Retrieve the amount of elapsed years between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed years between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedYears(Calendar before, Calendar after) {
        return elapsed(before, after, Calendar.YEAR);
    }

    /**
     * Add the given amount of years to the given calendar. The changes are reflected in the given
     * calendar.
     * @param calendar The calendar to add the given amount of years to.
     * @param years The amount of years to be added to the given calendar. Negative values are also
     * allowed, it will just go back in time.
     */
    public static void addYears(Calendar calendar, int years) {
        calendar.add(Calendar.YEAR, years);
    }

    /**
     * Retrieve the amount of elapsed months between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed months between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedMonths(Calendar before, Calendar after) {
        return elapsed(before, after, Calendar.MONTH);
    }

    /**
     * Add the given amount of months to the given calendar. The changes are reflected in the given
     * calendar.
     * @param calendar The calendar to add the given amount of months to.
     * @param months The amount of months to be added to the given calendar. Negative values are
     * also allowed, it will just go back in time.
     */
    public static void addMonths(Calendar calendar, int months) {
        calendar.add(Calendar.MONTH, months);
    }

    /**
     * Retrieve the amount of elapsed days between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed days between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedDays(Calendar before, Calendar after) {
        return elapsed(before, after, Calendar.DATE);
    }

    /**
     * Add the given amount of days to the given calendar. The changes are reflected in the given
     * calendar.
     * @param calendar The calendar to add the given amount of days to.
     * @param days The amount of days to be added to the given calendar. Negative values are also
     * allowed, it will just go back in time.
     */
    public static void addDays(Calendar calendar, int days) {
        calendar.add(Calendar.DATE, days);
    }

    /**
     * Retrieve the amount of elapsed hours between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed hours between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedHours(Calendar before, Calendar after) {
        return (int) elapsedMillis(before, after, 3600000); // 1h = 60m = 3600s = 3600000ms
    }

    /**
     * Add the given amount of hours to the given calendar. The changes are reflected in the given
     * calendar.
     * @param calendar The calendar to add the given amount of hours to.
     * @param hours The amount of hours to be added to the given calendar. Negative values are also
     * allowed, it will just go back in time.
     */
    public static void addHours(Calendar calendar, int hours) {
        calendar.add(Calendar.HOUR, hours);
    }

    /**
     * Retrieve the amount of elapsed minutes between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed minutes between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedMinutes(Calendar before, Calendar after) {
        return (int) elapsedMillis(before, after, 60000); // 1m = 60s = 60000ms
    }

    /**
     * Add the given amount of minutes to the given calendar. The changes are reflected in the given
     * calendar.
     * @param calendar The calendar to add the given amount of minutes to.
     * @param minutes The amount of minutes to be added to the given calendar. Negative values are
     * also allowed, it will just go back in time.
     */
    public static void addMinutes(Calendar calendar, int minutes) {
        calendar.add(Calendar.MINUTE, minutes);
    }

    /**
     * Retrieve the amount of elapsed seconds between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed seconds between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static int elapsedSeconds(Calendar before, Calendar after) {
        return (int) elapsedMillis(before, after, 1000); // 1sec = 1000ms.
    }

    /**
     * Retrieve the amount of elapsed time between the two given calendars based on the given
     * calendar field as definied in the Calendar constants, e.g. <tt>Calendar.MONTH</tt>.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @param field The calendar field as definied in the Calendar constants.
     * @return The amount of elapsed time between the two given calendars based on the given
     * calendar field.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    private static int elapsed(Calendar before, Calendar after, int field) {
        checkBeforeAfter(before, after);
        Calendar clone = (Calendar) before.clone(); // Otherwise changes are been reflected.
        int elapsed = -1;
        while (!clone.after(after)) {
            clone.add(field, 1);
            elapsed++;
        }
        return elapsed;
    }

    /**
     * Retrieve the amount of elapsed milliseconds between the two given calendars.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @return The amount of elapsed milliseconds between the two given calendars.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    public static long elapsedMillis(Calendar before, Calendar after) {
        return elapsedMillis(before, after, 1); // 1ms is apparently 1ms.
    }

    /**
     * Retrieve the amount of elapsed milliseconds between the two given calendars and directly
     * divide the outcome by the given factor. E.g.: if the division factor is 1, then you will get
     * the elapsed milliseconds unchanged; if the division factor is 1000, then the elapsed
     * milliseconds will be divided by 1000, resulting in the amount of elapsed seconds.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @param factor The division factor which to divide the milliseconds with, expected to be at
     * least 1.
     * @return The amount of elapsed milliseconds between the two given calendars, divided by the
     * given factor.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar or
     * if the division factor is less than 1.
     */
    private static long elapsedMillis(Calendar before, Calendar after, int factor) {
        checkBeforeAfter(before, after);
        if (factor < 1) {
            throw new IllegalArgumentException("Division factor '" + factor + "' should not be less than 1.");
        }
        return (after.getTimeInMillis() - before.getTimeInMillis()) / factor;
    }

    /**
     * Check if the first calendar is actually dated before the second calendar.
     * @param before The first calendar with expected date before the second calendar.
     * @param after The second calendar with expected date after the first calendar.
     * @throws IllegalArgumentException If the first calendar is dated after the second calendar.
     */
    private static void checkBeforeAfter(Calendar before, Calendar after) {
        if (before.after(after)) {
            throw new IllegalArgumentException("The first calendar should be dated before the second calendar.");
        }
    }
}