Chapter 9: Java
,ch09.6595 Page 159 Friday, March 25, 2005 2:47 PM Chapter 9 CHAPTER 9 Java Many Java developers like Integrated Development Environments (IDEs) such as Eclipse. Given such well-known alternatives as Java IDEs and Ant, readers could well ask why they should even think of using make on Java projects. This chapter explores the value of make in these situations; in particular, it presents a generalized makefile that can be dropped into just about any Java project with minimal modification and carry out all the standard rebuilding tasks. Using make with Java raises several issues and introduces some opportunities. This is primarily due to three factors: the Java compiler, javac, is extremely fast; the stan- dard Java compiler supports the @filename syntax for reading “command-line param- eters” from a file; and if a Java package is specified, the Java language specifies a path to the .class file. Standard Java compilers are very fast. This is primarily due to the way the import directive works. Similar to a #include in C, this directive is used to allow access to externally defined symbols. However, rather than rereading source code, which then needs to be reparsed and analyzed, Java reads the class files directly. Because the symbols in a class file cannot change during the compilation process, the class files are cached by the compiler. In even medium-sized projects, this means the Java com- piler can avoid rereading, parsing, and analyzing literally millions of lines of code compared with C. A more modest performance improvement is due to the bare mini- mum of optimization performed by most Java compilers.
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