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Commit 5898cc10 authored by Neil Fuller's avatar Neil Fuller
Browse files

Fix bug in Time.getJulianDay() 

Time is generally deprecated because it has various problems
including Y2038 issues. The static Time.getJulianDay() method
doesn't have Y2038 issues but it did have an issue with
negative millis values which is fixed in this commit.

See the associated cts change for improved tests.

Documentation has also been improved in this commit.

Bug: 16550209
Test: atest android.text.format.cts.TimeTest
Change-Id: Ia4092efc92a24cd5741b2a8dd75a0680008cce27
parent 3628bb3a

core/java/android/text/format/Time.java

+24 −13
Original line number Diff line number Diff line
@@ -937,9 +937,12 @@ public class Time { 
    }



    /**

     * Returns true if the day of the given time is the epoch on the Julian Calendar

     * (January 1, 1970 on the Gregorian calendar).

     *

     * Returns true if the instant of the supplied time would be for the

     * Gregorian calendar date January 1, 1970 <em>for a user observing UTC

     * </em>, i.e. the timezone of the time object is ignored.

     * <p>

     * See {@link #getJulianDay(long, long)} for how to determine the Julian day

     * for the timezone of the time object.

     * <p>

     * This method can return an incorrect answer when the date / time fields have

     * been set to a local time that contradicts the available timezone information.
@@ -949,31 +952,39 @@ public class Time { 
     */

    public static boolean isEpoch(Time time) {

        long millis = time.toMillis(true);

        return getJulianDay(millis, 0) == EPOCH_JULIAN_DAY;

        return getJulianDay(millis, 0 /* UTC offset */) == EPOCH_JULIAN_DAY;

    }



    /**

     * Computes the Julian day number for a point in time in a particular

     * timezone. The Julian day for a given date is the same for every

     * timezone. For example, the Julian day for July 1, 2008 is 2454649.

     * timezone. The Julian day for a given calendar date is the same for

     * every timezone. For example, the Julian day for July 1, 2008 is

     * 2454649.

     *

     * <p>Callers must pass the time in UTC millisecond (as can be returned

     * by {@link #toMillis(boolean)} or {@link #normalize(boolean)})

     * and the offset from UTC of the timezone in seconds (as might be in

     * {@link #gmtoff}).

     * and the offset from UTC of the timezone in seconds at that time (as

     * might be in {@link #gmtoff}).

     *

     * <p>The Julian day is useful for testing if two events occur on the

     * same calendar date and for determining the relative time of an event

     * from the present ("yesterday", "3 days ago", etc.).

     *

     * @param millis the time in UTC milliseconds

     * @param gmtoff the offset from UTC in seconds

     * @param gmtoffSeconds the offset from UTC in seconds

     * @return the Julian day

     * @deprecated Use {@link java.time.temporal.JulianFields#JULIAN_DAY} instead.

     */

    public static int getJulianDay(long millis, long gmtoff) {

        long offsetMillis = gmtoff * 1000;

        long julianDay = (millis + offsetMillis) / DateUtils.DAY_IN_MILLIS;

        return (int) julianDay + EPOCH_JULIAN_DAY;

    @Deprecated

    public static int getJulianDay(long millis, long gmtoffSeconds) {

        long offsetMillis = gmtoffSeconds * 1000;

        long adjustedMillis = millis + offsetMillis;

        long julianDay = adjustedMillis / DateUtils.DAY_IN_MILLIS;

        // Negative adjustedMillis values must round towards Integer.MIN_VALUE.

        if (adjustedMillis < 0 && adjustedMillis % DateUtils.DAY_IN_MILLIS != 0) {

            julianDay--;

        }

        return (int) (julianDay + EPOCH_JULIAN_DAY);

    }



    /**