Add a user library into a project

There are two steps to follow when you plan to add an exist library into your project. The library may be either yours or some public one.

As the first step, you need to create a new User Library for the adding library. Consider adding the jaxb ri-2.1.8 as an example.
1. Enter the Window menu and open the Preferences option.
2. Find the User Library which is hierarchically located under the Java->Build Path.
3. Make a new User Library with the New button, and put in an expected library name in the pop-up message box, say, JAXB. If you select the System library option, then this Libray would be added to the boot class path.
4. Click the Add JARs... button to add files to the new library. For the Jaxb, I add all the files in the folder of lib.
5.Click OK to make sure the setting. Then, Done!

As the second step, you need to add the created new User library into your project.
1.Enter the Project menu and open the Properties option.
2. Find the Libraries under the Java Build Path.
3. Click Add Library button, then click User Library and Next. Select the one you want to add,say,JAXB.
4.Click OK to make sure the setting.

Having finished these two steps, the expected library is added in your project.