IssueTracker

Lars, could you explain why not just using the java.time package exclusively does not work for you? Will the following work?

ZoneId = zoneId = ...
TimeZone tz = java.util.TimeZone.getTimeZone(zoneId.toString());

There is a difference between the 2 methods when you call .getID() on the resulting TimeZone instance

Considering the following example:

TimeZone.getTimeZone("GMT+02:00").getID() //results in "GMT+02:00"
TimeZone.getTimeZone("+02:00").getID() // results in "GMT" which is in my opinion incorrect

The output for zoneId.toString() doesn't include GMT thus resulting in the incorrect id.

This is fixed by the java.util.TimeZone.getTimeZone(ZoneId zoneId) method which adds the GMT information, as can be seen in the method body:

public static TimeZone getTimeZone(ZoneId zoneId) {
    String tzid = zoneId.getId(); // throws an NPE if null
    char c = tzid.charAt(0);
    if (c == '+' || c == '-') {
        tzid = "GMT" + tzid;
    } else if (c == 'Z' && tzid.length() == 1) {
        tzid = "UTC";
    }
    return getTimeZone(tzid);
}

Turned out we already had the desugaring support in place (https://github.com/google/desugar_jdk_libs/blob/master/src/share/classes/java/util/DesugarTimeZone.java#L160), but had missed it in the configuration.

The updated configuration has now finally been published, so with

dependencies {
  coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:1.0.10'
}

there is support for methods getTimeZone and toZoneId on java.util.TimeZone.

I just tested getTimeZone in the new version 1.0.10 on api25 and its seems to work,

however the linter in Android studio still flags the method with Call requires API level 26 (current min is 21): java.util.TimeZone#getTimeZone

(I also tried restarted Android studio and invalidated the caches)