Difference between adding library and .jar file in NetBeans?

I have a .jar file of LWUIT, and it's also in there in the NetBeans library. When I add it as a .jar file my programs run good and when I add it as a library my output is not show开发者_如何学Cn correctly. What's wrong with this?

When added as a library, LWUIT is only available for your application to compile against. I assume LWUIT is not already installed on whatever J2ME-enabled device/emulator you want to run your application.

When added to your application JAR file, LWUIT is also available for your application to run against. Your application JAR file is presumably significantly larger then.