Cross Platform

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Java is also cross platform. This means that a Java application can be run on a variety of computer systems, without any modification to the program. Java runs on many different platforms, but some of the more common ones include:

• Microsoft Windows
• Apple Macintosh
• Linux
• Cell phones and other embedded devices

Consider the program running in Figure 1.4. This is a Java application running under Windows XP. As you can see, it contains buttons, graphics and other features you would normally expect from a program. This application is written in Java, so it can run on systems other than Windows. You can see this program running under Windows in Figure 1.4.

Figure 1.4: A Java Application Running on Windows

This exact same program can be run under the Macintosh. This takes no changes at all. I simply copied the application to a CD-ROM and loaded it onto a Mac. The program runs and looks very similar to the Windows version, except that it more closely matches how a Macintosh application should look. Java always attempts to match the look and feel of the operating system it is running on. You can see the program running under Mac in Figure 1.5.

Figure 1.5: A Java Application Running on the Macintosh

You can download everything you will need to develop in Java for free. Java can be downloaded from Sun Microsystems’s site at http://java.sun.com. From this web page, choose the J2SE 5.0 option under the “Popular Downloads” section on the right side of your page.