Java™ Application Development on Linux - Dator

7.9 What You Still Don’t Know187obfuscation as other native compiled code. If you need to make your codeclosed and proprietary, gcj may be the right tool for you. Naturally, we aren’tvery fond of this idea, but it is still a reason one might choose the tool.Finally, we mentioned that speed wasn’t a certain factor for choosing gcj,but there is an exception. So far, 15 Java is particularly slow at starting andshutting down virtual machines. If you have a Java program that is invoked ondemand or in a loop and the VM is started and stopped on each invocation,then gcj will give you a huge speed improvement, even if the code executes atthe same speed or slightly slower than the JIT JVM code.7.7REASONS NOT TO USE GCJWe can think of three reasons not to use gcj. First, the compiled binary willrun only on the target platform, whereas a Java bytecode binary is portable toany Java runtime without modification or recompilation. Second, gcj is notdefinitive. Sun still “owns” Java and only Sun’s implementation can be presumedto be “correct.” Third, the gcj API classes are not complete. If you visitthe API status page we mentioned earlier, you can see what is provided andwhat is not. If gcj lacks an API your application requires, then you can be suregcj is not the tool for you.7.8REVIEWThe GNU Compiler for Java is part of the GNU Compiler Collection. It isgenerally used to compile Java source code into native binaries. It providesmany of Sun’s API classes, but not all.7.9WHAT YOU STILL DON’T KNOWYou do not know how to interface with C/C++ code using gcj. You do notknow how to use SWT from Eclipse to write GUI apps with gcj.15. Sun claims that Java 5.0 will show considerable improvement in VM initialization speed.