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https://issues.apache.org/jira/browse/LANG-379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12557643#action_12557643
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Robert Scholte commented on LANG-379:
-------------------------------------
Examples can be provided
And for the "Why"-part: I've come with a couple of reasons. One of the
applications I've worked with used events over some period every day. The way
this is stored was a startdate, an enddate plus the starttime and endtime in
seconds. I was looking for a DateUtils.round, but then the other way around, by
ingoring year, months, etc. Since this was part of the core, I saw developers
reinventing the proper calculation, often resulting in the wrong solution the
first time. So I introduced these methods.
With this in mind I thought it could be interesting to make the unit variable.
And after that the unit.
You can think of a reverse version counting down the days till the next year or
month.
As I mentioned: The most interesting reason I think for including this, is
because it's the opposite of DateUtils.round
> Calculating A date fragment in any time-unit
> --------------------------------------------
>
> Key: LANG-379
> URL: https://issues.apache.org/jira/browse/LANG-379
> Project: Commons Lang
> Issue Type: New Feature
> Affects Versions: 2.3
> Reporter: Robert Scholte
> Priority: Minor
> Fix For: 2.4
>
> Attachments: DateUtils-fragments.patch, DateUtilsFragmentTest.java
>
>
> These DateUtils-features can make it possible to calculate a date-part in any
> time-unit. For example: the number of minutes of this year, the number of
> seconds of today, etc.
> I've started with some coding, and if there's enough interest we can make it
> more solid.
> public static long getFragmentInSeconds(Date date, int fragment) {
> return getFragment(date, fragment, Calendar.SECOND);
> }
>
> public static long getFragmentInMinutes(Date date, int fragment) {
> return getFragment(date, fragment, Calendar.MINUTE);
> }
>
> public static long getFragmentInHours(Date date, int fragment) {
> return getFragment(date, fragment, Calendar.HOUR_OF_DAY);
> }
>
> public static long getFragmentInDays(Date date, int fragment) {
> return getFragment(date, fragment, Calendar.DAY_OF_YEAR);
> }
> public static long getFragmentInSeconds(Calendar calendar, int
> fragment) {
> return getFragment(calendar, fragment, Calendar.SECOND);
> }
>
> public static long getFragmentInMinutes(Calendar calendar, int
> fragment) {
> return getFragment(calendar, fragment, Calendar.MINUTE);
> }
>
> public static long getFragmentInHours(Calendar calendar, int fragment) {
> return getFragment(calendar, fragment, Calendar.HOUR_OF_DAY);
> }
>
> public static long getFragmentInDays(Calendar calendar, int fragment) {
> return getFragment(calendar, fragment, Calendar.DAY_OF_YEAR);
> }
>
> private static long getFragment(Date date, int fragment, int unit) {
> Calendar calendar = Calendar.getInstance();
> calendar.setTime(date);
> return getFragment(calendar, fragment, unit);
> }
> private static long getFragment(Calendar calendar, int fragment, int
> unit) {
> long millisPerUnit = getMillisPerFragment(unit);
> long result = 0;
> switch (fragment) {
> case Calendar.YEAR:
> result += (calendar.get(Calendar.DAY_OF_YEAR) *
> MILLIS_PER_DAY) / millisPerUnit;
> case Calendar.MONTH:
> result += (calendar.get(Calendar.DAY_OF_MONTH) *
> MILLIS_PER_DAY) / millisPerUnit;
> case Calendar.DAY_OF_YEAR:
> case Calendar.DATE:
> result += (calendar.get(Calendar.HOUR_OF_DAY) *
> MILLIS_PER_HOUR) / millisPerUnit;
> case Calendar.HOUR_OF_DAY:
> result += (calendar.get(Calendar.MINUTE) *
> MILLIS_PER_MINUTE) / millisPerUnit;
> case Calendar.MINUTE:
> result += (calendar.get(Calendar.SECOND) *
> MILLIS_PER_SECOND) / millisPerUnit;
> case Calendar.SECOND:
> result += (calendar.get(Calendar.MILLISECOND) * 1) /
> millisPerUnit;
> }
> return result;
> }
>
> private static long getMillisPerFragment(int fragment) {
> long result = Long.MAX_VALUE;
> switch (fragment) {
> case Calendar.DAY_OF_YEAR:
> case Calendar.DATE:
> result = MILLIS_PER_DAY;
> break;
> case Calendar.HOUR_OF_DAY:
> result = MILLIS_PER_HOUR;
> break;
> case Calendar.MINUTE:
> result = MILLIS_PER_MINUTE;
> break;
> case Calendar.SECOND:
> result = MILLIS_PER_SECOND;
> break;
> case Calendar.MILLISECOND:
> result = 1;
> break;
> }
> return result;
> }
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