# JAVA Environment Setup on Windows

I start to play antlr and before that I need to setup java environment on my windows box.

2. Install JDK(e.g. C:\Program Files\Java\jdk1.7.0_03) and setup JAVA_HOME, PATH, CLASSPATH environment variable
• Add JAVA_HOME as “C:\Program Files\Java\jdk1.7.0_03″. JAVA_HOME represents the root directory of JDK. This serves two purposes:
1. Other JAVA related paths are constructed relative to JAVA_HOME. Thus if SDK is upgraded, only JAVA_HOME needs to be changed.
2. Some third party software assumes JAVA_HOME is properly setup.
• Append %JAVA_HOME%\bin to PATH. So command like ” java”, “javac” can be run on command line without providing the absolute path. One interesting thing I notice is “java”, “javaw”, “javaws” are duplicated under C:\Windows\System32 which is already included in PATH. So really, even without doing this step, “java” can still be run without the absolute path.
• Add CLASSPATH. First I create a folder at %JAVA_HOME%..\local\lib for putting any external java classes. In my case, I put “antlr-3.4-complete.jar” there. Thus my CLASSPATH is set to “.;antlr-3.4-complete.jar;” Notice the leading “.” which stands for the current directory.

That’s it. I haven’t done java since I left school. It’s a good exercise anyway. Antlr website also has a short guide on setting this up.