Why Choose Java for Mobile Game Development?

Although C++ has the advantage of being compiled into native code with direct access to system resources, and with BREW the platform provides end-to-end solutions to mobile game developers while allowing them to work with any desired language (including C++, Java, XML, and Flash).

              Java is the most popular choice for game development. Java, or the Java 2 Micro Edition (J2ME) platform to be precise, is identified as the most convenient for developing mobile games. (For more specifics on J2ME, see "What is Java 2 Micro Edition?") The driving forces behind J2ME's popularity are:

• J2ME enjoys the status of an industry standard backed by all major handset makers, with most of the present day mobile phones being Java-enabled.
• J2ME is a free and open platform. This helps keep the development costs low and provides the necessary flexibility with ample support freely available for developers using it.
• Its highly portable nature ("Write once run anywhere") ensures that a game application written for one brand/type of handset will work with all other brands/types of Java-enabled handsets.
• It is especially optimized for small devices, is lightweight, and is highly secure because applications written on it cannot access or affect other applications running on the phone/device.
• J2ME consists of the Mobile Information Device Profile (MIDP) API that is designed specifically for developing applications for mobile devices including mobile phones, keeping in mind their limitations and constraints. Furthermore, the latest MIDP version 2.0 itself dedicates a whole API to game development, making game development simpler and quicker.

Now, you will explore MIDP 2.0 the in context of mobile gaming.

The Role of MIDP 2.0 in Game Development

MIDP 2.0 API is a set of feature-loaded APIs used for developing secure, rich-content multimedia applications, including games, for mobile devices. MIDP 2.0 builds upon its predecessor MIDP 1.0 to provide a better development platform for building efficient and fast mobile applications. For more information on MIDP 2.0, see the Resources section at the end of this article.

MIDP 2.0 further refines the features and functionalities provided by MIDP 1.0. For information on the new features, see What's New in MIDP 2.0. One of the important additions made to MIDP is the Game API, or the javax.microedition.lcdui.game API package to be precise. Through the Game API, MIDP 2.0 provides game developers with the readymade building blocks that were to be developed from scratch in the case of MIDP 1.0. These building blocks are classes for creating and controlling various game elements such as game canvas, sprites, layers, and so forth (these are explained in the next section). Thus, MIDP 2.0 significantly reduces the time involved in game development.

The other two MIDP 2.0 API packages essential for game development, also explored by this article, are javax.microedition.midlet and javax.microedition.lcdui.

The javax.microedition.midlet API package provides a base for developing all mobile applications. It contains the javax.microedition.midlet.MIDlet class, which is the base class of all J2ME-based mobile applications (also known as midlets) and must be extended by the main classes of all mobile applications. Quite similar to the java.applet.Applet class, the MIDlet class provides resources necessary to create midlets.

The javax.microedition.lcdui API package is necessary to develop a user interface (UI) for all types of mobile applications. This API provides classes to create and control UI components (such as screen, form, text box, radio buttons, and so on) and processing input for mobile applications, including games. Developers who have GUI development experience with AWT and SWING will find that the elements of the javax.microedition.lcdui package are similar to elements from these APIs.

I'll discuss the elements of these APIs relevant to game development as upi encounter them during the development of the example game app.

Building the Example Game

To understand the APIs and their respective classes better, you'll start developing a simple mobile game. This will be a solo player offline game, a car moving through an obstacle course. The player uses the left and right handset keys to "steer" the running car to the left or right to keep it from colliding into an obstacle. The game is over when a collision happens and the score is displayed. I'll call it HardDrive.

Note: The example game is developed using the J2ME Wireless Toolkit 2.1_01 and J2SE 1.4.2_07 SDK on a Windows 2000 platform. Other versions of both the Wireless Toolkit and J2SE SDK that are compatible with various platforms are also available.

Begin building the game app by putting together the source code; call it HardDrive. From what you've explored in the previous section, the first thing you need develop is the HardDriveMIDlet (HardDriveMIDlet.java) that extends the javax.microedition.midlet.MIDlet class.