Running the Hello World Application
Now come back to the WTK window and from the Menu select Project->Run. If there are no errors, then this will Compile, Preverify, Package, and run the HelloWorldApp in the Emulator. The Emulator Window is shown in Figure 7.

To run the Hello World Application, you have to click on the button below the 'Launch' item (marked with a red box).

This will execute the application and you will see the message “Hello World”.

Figure 5: Messages

Deploying the Hello World App on a Mobile Device
Before continuing, please refer to the Manual of your Mobile Device for details of support of J2ME, method for connecting your device to your PC to copy files and also check the method for installing J2ME Applications on your device.

You can create the package for deploying to the Mobile Device by selecting from the Menu Project->Package->Create Package.

This will create the JAR file and the JAD file in a bin folder (at the same level as the src folder). In my case this is

D:\Users\Sudipto Chanda\j2mewtk\2.5.2\apps\HelloWorldApp\bin

Now copy the files (HelloWorldApp.jar and HelloWorldApp.jad) to your mobile device using the USB/IrDA/WLAN or whichever connectivity method given for your mobile. On the device, locate the folder where you copied the files and click on the JAD file to install the Hello World MIDlet on your Mobile. Now you can run the MIDlet on your Mobile by clicking on it or as per the procedure given in your manual.

Figure 5: Emulator

Conclusion
As you can see, it is really easy to create MIDlets and test them on the PC and deploy on mobile devices. The applications will run on most modern mobile phones. The Java ME platform also provides multimedia and 3D Graphics support for rich applications likes Games. There are many demo applications you can play around with to get the hang of the tools. You'll find them in C:\WTK2.5.2\apps.