Device-Specific Libraries

You've seen how J2ME does a great job of abstracting the features of an MID. The MIDP API gives you the comfort of working with a (relatively) standard platform to develop your games. MIDP 1.0 represents the features that are common to all MIDs that support that version. There are some exceptions where support is optional, such as repeating keys and pointer device input. Generally, though, what you see in the specifications is what you can expect to get.

As you can imagine, many mobile devices have features beyond those supported by MIDP 1.0especially features that are unique to particular devices (such as vibration support). This will naturally continue as the hardware improves. The MIDP specifications will continue to be updated. You'll notice that many of the features made available as manufacturer-specific extensions under MIDP 1, such as transparent images and sounds, are now included in MIDP 2. However, it is the nature of a standardized common platform to leave room for manufacturer extensions.

Manufacturers make additional features available to developers through J2ME software development kits (SDKs). For example, Nokia provides an SDK for many of their devices, which provide features such as transparent image blitting, playing sounds, and turning the device into a vibrator (settle down).

You also need to regularly test, if not directly develop, using the various emulators supported for different phones. Trust me; switch phones regularly during development to keep some perspective on the idiosyncrasies of different devices. It'll save you from some monster surprises later.

In the next few sections, you'll take a look at the features made available by some of the more popular MID manufacturers: Nokia, Siemens, and Motorola.