Java: CLASSPATH

Where Java finds programs

A common way to compile and run a simple Java program is with commands like the following.

    javac MyProgram.java
    java MyProgram

Or you may use an IDE that permits you to compile and run. In any case, Java must know, both for compilation and execution of the programs, where to find any library classes that are used. Java (at least after version 1) knows how to find it's own classes, but you have to tell it where to find other libraries you may be using. The standard Microsoft Windows directories are not searched.

You may need to specify a list of directories or jar files where programs can be found by setting the environment variable CLASSPATH.

Setting CLASSPATH on Windows XP

The CLASSPATH variable can be set on Windows XP with the following steps.

Click the Start button in the lower left of the screen.
Select Control Panel from the pop-up menu.
Choose System from the submenu.
Click the Advanced tab.
Click the Environment Variables button near the bottom. You will now see tow lists of variables.
Look in the System variables list for a variable named CLASSPATH. If you find it, click Edit. If you don't find it, click New and enter CLASSPATH in the Variable name field.
The Variable value field is a list of file paths of directories or jar files.

References

A more complete explanation of CLASSPATH can be found in Java Glossary : classpath.