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Java compiler 159
Java compiler
A Java compiler is a compiler for the Java programming language. The most common form of output from a Java
compiler are Java class files containing platform-neutral Java bytecode. There exist also compilers emitting
optimized native machine code for a particular hardware/operating system combination.
Most Java-to-bytecode compilers, Jikes being a well known exception, do virtually no optimization, leaving this
until runtime to be done by the JRE.
The Java Virtual Machine (JVM) loads the class files and either interprets the bytecode or just-in-time compiles it to
machine code and then possibly optimizes it using dynamic compilation.
The very first Java compiler developed by Sun Microsystems was written in C using some libraries from C++.
Major Java compilers
As of 2010, the following are major Java compilers:
• javac, included in JDK from Sun Microsystems, open-sourced since 13 November 2006.
• GCJ, a part of gcc which compiles C, Fortran, Pascal and other programming languages besides Java. It can also
generate native code using the back-end of gcc.
• ECJ, the Eclipse Compiler for Java, is an open source incremental compiler used by the Eclipse JDT.
Java decompilers
A Java decompiler tries to reverse the process of compiling, that is it tries to decompile Java bytecode files (*.class)
back to Java source files (*.java).
• DJ Java Decompiler [1] (Uses JAD) 10 use trial version
• JAD, written in C++, free for non-commercial use.
• JD [1], younger project, includes GUI, optional Eclipse-plugin.
• JODE [2], decompiler and optimizer, open-source.
• Mocha, one of the first decompilers for Java.
External links
• Sun's OpenJDK javac page [3]
• Jikes homepage [4]
• JSR 199 [5] Java Compiler API Java Specification Request for invoking the Java compiler from a Java program
References
[1] http:/ / www. neshkov. com/
[2] http:/ / jode. sourceforge. net/
[3] http:/ / openjdk. java. net/ groups/ compiler/
[4] http:/ / jikes. sourceforge. net/
[5] http:/ / www. jcp. org/ en/ jsr/ detail?id=199