I'm working on a basic Java project to make me more comfortable with the language (I've just started learning), and have come across a problem when trying to use a 3rd party library - I'm trying to use Apache's Lang library. I'm not using Eclipse to write my program, which I believe has a tool which makes it easy to use 3rd party libraries, so I'm not sure how I can use this library. When I try to use it, the 2 errors I receive are 'error: package org.apache.commons.lang3 does not exist', and 'error: cannot find symbol' on the line in which I call the StringUtils class (part of the Lang library). How can I use the library? (I am definitely a beginner in Java).


What you're going to need to learn about is the Java classpath. In order to use a third party JAR, it needs to be on the classpath when executing your code.

Here is an excellent StackOverflow post which explains how to accomplish this.

  • Thanks - I think that helped a lot. The only problem is, I now cannot run the project, as it gives me an 'Error: Could not find or load main class' error, 'Caused by: java.lang.ClassNotFoundException: MyProgram'. There is no compilation error, but just an error when I run the class. Any ideas? (The command I use to run the class is 'java -cp lib/commons-lang3-3.5.jar MyProgram') – JAUER Aug 13 at 22:17

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