The classpath is one of the most complex and infuriating parts of the Java™ platform, but mastering it is essential to becoming a professional Java programmer. Here you can find two usefull links about this subject.
1. Managing the Java classpath (UNIX and Mac OS X)
2. Managing the Java classpath (Windows)
Both of these articles are written by Mr.Elliotte Rusty Harold in IBM developerWorks.
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