Java/Android判断两个时间戳是否在同一天

public static boolean isSameDay(long millis1, long millis2, TimeZone timeZone) {
        long interval = millis1 - millis2;
        return interval < 86400000 && interval > -86400000 && millis2Days(millis1, timeZone) == millis2Days(millis2, timeZone);
    }

    private static long millis2Days(long millis, TimeZone timeZone) {
        return (((long) timeZone.getOffset(millis)) + millis) / 86400000;
    }