How to use org.apache.commons.lang namespace in Java?

Question

I tried in Eclipse to use org.apache.commons.lang.NotImplementedException, though it seems from what I can see both from IntelliSense and the

Answer 1

You need to add Apache commons jar file to the project. You can select the jar you want from here - http://commons.apache.org/downloads/index.html
for lang you need this - commons-lang-2.5.jar

Answer 2

Download the commons lang library and add it to your eclipse project library.

EDIT (2016/02) : it seems that nowadays the .jar files are not provided as is. You have to get the "binary" archive (e.g. "commons-lang3-3.4-bin.zip") from the same download page and extract it. The required jar files are inside the extracted folder.

To add the jar to your eclipse project library:

1. open project properties
2. choose Java Build Path
3. tab to Libraries
4. add jars (if the jar is inside your project folder)
5. add external jar (if the jar is outside your project folder)