Question: I am trying to do "javac Classname.java" from cmd prompt, and this Classname.java requires Jfreechart libraries/jars, and runs fine if compiled from Eclipse (because project package has jars imported).

But I want to run the file from cmd prompt and its not able to show me the output. It comes with errors like: ("package doesn't exist"), how to fix it? I need the class file and also run JNI commands to create header file.

Answer: 
You need to [set the classpath](http://download.oracle.com/javase/6/docs/technotes/tools/windows/classpath.html).

You can do this in 2 ways. Either use the `-classpath` or `-cp` option:

```
javac -cp jar1.jar;path/to/jar2.jar Classname.java

```

Or, if you need it to persist, use the `CLASSPATH` environmental variable:

```
set CLASSPATH=path1;path2
javac Classname.java

```
You just need to add the directory paths and/or .jar libraries to your "-classpath" command-line argument.

Depending on how many libraries you've got, you might well wind up with a .sh script (Linux) or .cmd file (windows) that looks something like this:

<http://ubuntuforums.org/showthread.php?t=230258>

```
java -cp jts.jar:jcommon-1.0.0.jar:jfreechart-1.0.0.jar:jhall.jar:other.jar:rss.jar -Xmx256M jclient.LoginFrame .

```

If you're on Windows, you'd use ";" as a separator (instead of \*nix ":").

'Hope that helps!