How to attach libraries to JAR file?

Question

It works fine when compiling project, but after exporting it to a runnable jar and launching, it can't find external files and throws an error. What should I do?

Answer 1

Add external libraries to the manifest.mf:

Class-Path: . MyApp_lib/extlib.jar MyApp_lib/extlib2.jar ...

Answer 2

You could attempt building a fat jar that includes all the jars. It contains a custom class loader to load the jars referenced externally by your project.

Try using http://fjep.sourceforge.net/ plugin to build a fat jar.

You can export a java project containing jars using the File -> Export -> Other -> One Jar Exporter.

The jar thus exported works fine.

Answer 3

You have to keep all required jars in the classpath to run your jar. Run your jar like :

java -cp extlib/* -jar yourjar.jar OR java -cp lib1.jar:lib2.jar:.. -jar yourjar.jar

Answer 4

Make sure that while building the jar, you include all the used libraries(include everything from class path). This issue will happen when you refer a external jar.

Answer 5

You can include a classpath variable in the jar's manifest file.

JAR file classpath