How do you convert 2 dates one in BST(Current date) and the other in GMT so that the can be compared date before and after methods?

Question

How do you convert 2 dates one in BST(Current date) and the other in GMT so that they can be compared using the calendar date before() and after() methods? I don\'t know if BS

Answer 1

I had the same problem and finding the answer was not evident. We are using this solution in production now and it works fine. It's based on jodatime library

public static Date convertDateTimeZone(Date date, TimeZone currentTimeZone, TimeZone newTimeZone) {
    return convertJodaTimezone(new LocalDateTime(date), DateTimeZone.forTimeZone(currentTimeZone), DateTimeZone.forTimeZone(newTimeZone));
}

public static Date convertDateTimeZone(Date date, TimeZone newTimeZone) {
    return convertDateTimeZone(date, null, newTimeZone);
}

public static Date convertJodaTimezone(LocalDateTime date, String srcTz, String destTz) {
    return convertJodaTimezone(date, DateTimeZone.forID(srcTz), DateTimeZone.forID(destTz));
}

public static Date convertJodaTimezone(LocalDateTime date, DateTimeZone srcTz, DateTimeZone destTz) {
    DateTime srcDateTime = date.toDateTime(srcTz);
    DateTime dstDateTime = srcDateTime.withZone(destTz);
    return dstDateTime.toLocalDateTime().toDateTime().toDate();
}

All you have to do is to use the first method to convert your dates into a specific common Timezone and do the comparaison.

To get the timezone instance all you have to do is :

TimeZone.getTimeZone("BST");