Thursday, September 09, 2010

NoClassDefFoundError in BlackBerry

I have been struggling a few days with a strange error in BlackBerry. My app works fine in the emulator, but when you start it on BlackBerry Bold (software version 4.5) you get a NoClassDefFoundError. On BlackBerry Storm (software version 4.6) it works fine, but on Bold2 (version 5.0) again you get NoClassDefFoundError.

The documentation says:
Thrown if the Java Virtual Machine tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found.

The searched-for class definition existed when the currently executing class was compiled, but the definition can no longer be found.

I have gone through all the changes since the last working version and I finally found it. I had added some fields like this:

fldPortHttp = new TextField("Port:", "", 20, Field.EDITABLE | BasicEditField.FILTER_NUMERIC);

This worked well, with no compilation errors and in the emulator, but caused the NoClassDefFoundError at runtime. The solution was simply to change to:

fldPortHttp = new BasicEditField("Port:", "", 20, Field.EDITABLE | BasicEditField.FILTER_NUMERIC);

Sunday, May 09, 2010

The future for mobile java

The last three years or so I have worked mostly with mobile java, starting with Java ME and later moving into BlackBerr and Android. A lot of things has happened, three ears ago Android existed, but ther were hardly any phones available and BlackBerry did exist, but I knew nothing about it.

Today the future of Java ME is uncertain. Programming in Java is a good option on most mobile platforms (except iPhone), but the strongest alternatives are Android and BlackBerry, not Java ME.

There are of course different reasons for this. On the technical side, the User Interface options are very limited. LCDUI is very restricted, you very quickly end up with skipping the higher level API, because it is too restricted, and using the Canvas API, where you basically have to paint everything yourself. Doing input in a canvas based interface is difficult, you can react on key down and up, but the standard does not really allow you to tell if the devices even has a keyboard, or if you need to display a virtual keyboard on the screen.

An even worse problem is the fragmentation of the market. Java implementations differ, and even if it is very probable that your java me code will run on most devices (if it is well written) verifying that it does is not a smal task. And if you want it too look good it is even worse. Emulators do not help much either, verifing that something runs in the emulator does not guarantee that it will work on the device. And it is not even sure that there is an emultor for your target device.

And phone manufacturers keep making new models all the time... Apple basically has one platform and offers upgrade for old versions (sometimes free of charge, sometimes at a small charge) but the competition has not learned from this. Instead they have incompatible version on different devices, where you basically have to test on, if not all, several different versions. Just keeping up with the new models from the main manufacturers ( there are only four or five) takes a lot of time. The so called java verification does not guarantee that your application will run on all Java ME implementations with the features you need, instead you have to verify it again and again as there are new devices.

All in all this leads to that Java ME is not a good alternative for your application development today. The future of java om the mobile is rather in Android or BlackBerry. That is if not one of the major manufacturers take steps to fix this. And frankly I don't see this happening.

An exception to this is possibly Symbian. Java ME implementation on Symbian is pretty good. But it seems like Nokia is more interested in promoting development in C++, or rather the very restricted C++ available on Symbian.

Wednesday, January 06, 2010

New Antenna release

Today I released version 1.2.1 of Antenna. The new version includes both bug fixes and new features.

I made a mistake in the 1.2.0 release, which leads to a Null Pointer Exception if the Wireless Toolkit can not be detected. Antenna can detect a lot of toolkit's, but not all, so this has given users some poblems. A patch has been in the repository for a whil, but now it is in a release also.

When the 1.2.0 release was made, ther was no Java ME SDK for Mac available, but now there is. Unfortunately the file we used in 1.2.0 to detect Java ME SDK 3.0 is not included in the Mac version, so toolkit detection fails. This is fixed in the 1.2.1 release, which should work with Java ME SDK for Mac ( I haven't tested it myself, since I don't have a mac).

The realease also includes som contributed patches:
- obfusactor arguments can now be passed to WtkPackage
- Key stor type can be set in WtkSign
- WtkRapc can build libraries

More info on antenna and the release is available here.

Friday, January 01, 2010

Supporting BlackBerry touch devices

Our BlackBerry application is built using BlackBerry software version 4.5. Unfortunately this means that we can not handle touch events, since they are only supported from version 4.7. Since most of our users have 4.5 or 4.6 this is not an option. Up til now the application has had very limited functionality on touch devices like BlackBerry Storm, running in the so called *compatibility mode' with the virtual keyboard displayed all the time and only about half the screen available for our application.

But now we have made a few changes:
We upgraded the Storm device software (to version This solved the problem with the virtual keyboard, which now can be displayed only when needed.

We revised our application. The main problem is our custom object, which did not work well. This seems to be because the navigationMovement method is not called on a touch device. Since we had some application logic in this method in our custom object, it did not work well. The solution was to move the code to the moveFocus mthod, which is called both on touch and keyborad devices.

In the long run we probably will have to provide different installations for users with 4.5/4.6 or 4.7 software version. Still we do not support more advanced touch screen usage.