Android Java - Joda Date is slow

android, jodatime

Solution

I also ran into this problem. Jon Skeet's suspicions were correct, the problem is that the time zones are being loaded really inefficiently, opening a jar file and then reading the manifest to try to get this information.

However, simply calling `DateTimeZone.setProvider([custom provider instance ...])` is not sufficient because, for reasons that don't make sense to me, DateTimeZone has a static initializer where it calls `getDefaultProvider()`.

To be completely safe, you can override this default by setting this system property before you ever call anything in the joda.

In your activity, for example, add this:

@Override
public void onCreate(Bundle savedInstanceState) {
    System.setProperty("org.joda.time.DateTimeZone.Provider", 
    "com.your.package.FastDateTimeZoneProvider");
}

Then all you have to do is define `FastDateTimeZoneProvider`. I wrote the following:

package com.your.package;

public class FastDateTimeZoneProvider implements Provider {
    public static final Set<String> AVAILABLE_IDS = new HashSet<String>();

    static {
        AVAILABLE_IDS.addAll(Arrays.asList(TimeZone.getAvailableIDs()));
    }

    public DateTimeZone getZone(String id) {
        if (id == null) {
            return DateTimeZone.UTC;
        }

        TimeZone tz = TimeZone.getTimeZone(id);
        if (tz == null) {
            return DateTimeZone.UTC;
        }

        int rawOffset = tz.getRawOffset();

            //sub-optimal. could be improved to only create a new Date every few minutes
        if (tz.inDaylightTime(new Date())) {
            rawOffset += tz.getDSTSavings();
        }

        return DateTimeZone.forOffsetMillis(rawOffset);
    }

    public Set getAvailableIDs() {
        return AVAILABLE_IDS;
    }
}

I've tested this and it appears to work on Android SDK 2.1+ with joda version 1.6.2. It can of course be optimized further, but while profiling my app (mogwee), this decreased the DateTimeZone initialize time from ~500ms to ~18ms.

If you are using proguard to build your app, you'll have to add this line to proguard.cfg because Joda expects the class name to be exactly as you specify:

-keep class com.your.package.FastDateTimeZoneProvider

Problem

Original source