Which ArcObjects Java library should be referenced in ArcGIS Server installation envrionment?

Answer

When working with applications developed with ArcObjects SDK for Java, the arcobjects.jar library from its running environment must be referenced. In an environment with ArcGIS Server installed, the library named arcobjects.jar can be found in the following path:

<ArcGIS Server installation directory>\framework\lib\arcobjects.jar

or

<ArcGIS Server installation directory>\framework\runtime\ArcGIS\framework\lib\arcobjects.jar

Which file should be used for the application?

The file that should be referenced is:

<ArcGIS Server installation directory>\framework\lib\arcobjects.jar

When developing with the ArcObjects SDK for Java and ArcGIS Eclipse plug-ins, the ArcObjects Library from ArcGIS Server can be added if it's available in the same environment. Notice that this updates the build path with the arcobjects.jar file from the same aforementioned path.