@Override public long truncate(long t) { if (isCompound) { try { return truncateMillisPeriod(t); } catch (UnsupportedOperationException e) { return truncateCompoundPeriod(t); } } final int years = period.getYears(); if (years > 0) { if (years > 1 || hasOrigin) { int y = chronology.years().getDifference(t, origin); y -= y % years; long tt = chronology.years().add(origin, y); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.years().add(tt, -years); else t = tt; return t; } else { return chronology.year().roundFloor(t); } } final int months = period.getMonths(); if (months > 0) { if (months > 1 || hasOrigin) { int m = chronology.months().getDifference(t, origin); m -= m % months; long tt = chronology.months().add(origin, m); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.months().add(tt, -months); else t = tt; return t; } else { return chronology.monthOfYear().roundFloor(t); } } final int weeks = period.getWeeks(); if (weeks > 0) { if (weeks > 1 || hasOrigin) { // align on multiples from origin int w = chronology.weeks().getDifference(t, origin); w -= w % weeks; long tt = chronology.weeks().add(origin, w); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.weeks().add(tt, -weeks); else t = tt; return t; } else { t = chronology.dayOfWeek().roundFloor(t); // default to Monday as beginning of the week return chronology.dayOfWeek().set(t, 1); } } final int days = period.getDays(); if (days > 0) { if (days > 1 || hasOrigin) { // align on multiples from origin int d = chronology.days().getDifference(t, origin); d -= d % days; long tt = chronology.days().add(origin, d); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.days().add(tt, -days); else t = tt; return t; } else { t = chronology.hourOfDay().roundFloor(t); return chronology.hourOfDay().set(t, 0); } } final int hours = period.getHours(); if (hours > 0) { if (hours > 1 || hasOrigin) { // align on multiples from origin long h = chronology.hours().getDifferenceAsLong(t, origin); h -= h % hours; long tt = chronology.hours().add(origin, h); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.hours().add(tt, -hours); else t = tt; return t; } else { t = chronology.minuteOfHour().roundFloor(t); return chronology.minuteOfHour().set(t, 0); } } final int minutes = period.getMinutes(); if (minutes > 0) { // align on multiples from origin if (minutes > 1 || hasOrigin) { long m = chronology.minutes().getDifferenceAsLong(t, origin); m -= m % minutes; long tt = chronology.minutes().add(origin, m); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.minutes().add(tt, -minutes); else t = tt; return t; } else { t = chronology.secondOfMinute().roundFloor(t); return chronology.secondOfMinute().set(t, 0); } } final int seconds = period.getSeconds(); if (seconds > 0) { // align on multiples from origin if (seconds > 1 || hasOrigin) { long s = chronology.seconds().getDifferenceAsLong(t, origin); s -= s % seconds; long tt = chronology.seconds().add(origin, s); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.seconds().add(tt, -seconds); else t = tt; return t; } else { return chronology.millisOfSecond().set(t, 0); } } final int millis = period.getMillis(); if (millis > 0) { if (millis > 1) { long ms = chronology.millis().getDifferenceAsLong(t, origin); ms -= ms % millis; long tt = chronology.millis().add(origin, ms); // always round down to the previous period (for timestamps prior to origin) if (t < tt) t = chronology.millis().add(tt, -millis); else t = tt; return t; } else { return t; } } return t; }