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https://issues.apache.org/jira/browse/LANG-379?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12557540#action_12557540
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Henri Yandell commented on LANG-379:
------------------------------------
Valid point on Calendar/Date - the API already does lots of
Calendar.getInstance().setTime. So I'll retract that.
On ERA/YEAR etc, I get it now. I had unit and fragment confused; fragment is
the user-passed in one.
=-=-=-=
Second round of thoughts (we've been burnt on time based code in Lang before
and so have a strong justify it attitude):
Code examples in the Javadoc are definitely going to be needed - looking at the
javadoc it isn't clear to me what the methods do exactly. I had to walk through
the code before I properly understood (and with the drop-through on the switch
statement, it involves a little bit of time to notice that's not a standard
idiom). So - examples please :)
I'm also not sure "Why?" :) Why would I want the number of seconds of this
year? Or the number of minutes this month?
> 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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