I am new in BlackBerry application development. I have installed "BlackBerry Plug-ins for Eclipse version 7.1" successfully. Now I am trying to import one existing project into Eclipse, it is showing the following error:
Build path entry is missing: org.eclipse.jdt.lau...de.BlackBerryVMInstallType/BlackBerry JRE 4.7.0
what is the reason for this?
If you have only installed the OS 7.1 plugin, then you won't be able to target OS 4.7.
You'll need to also install the SDK for OS 4.7. To do that, in Eclipse, go to the Help menu, then Install New Software..., then select the Work With: pull-down menu, and pick the BlackBerry Eclipse Plugin site.
Then, in the center of the window, you'll select the SDKs (OS Versions) you want to directly target:
As you see, I'm using the Mac Eclipse Plugin, and it doesn't even show OS 4.7 ... I can't remember if the Windows versions still supports 4.7 (I think it might offer a 4.5 plugin). Basically, all the 4.7 devices out there should be eligible for free upgrades to 5.0, so I don't know that it's worth it to support 4.7 anymore. Just support OS 5.0+.
Once you're sure that you have the correct SDK, then in the window you show in your screenshot, try removing that OS 4.7 library. Then, use the Add Library.. button, select JRE System Library and pick the BlackBerry JRE 5.0.0 (it may be in the Alternate JRE menu):
After you do that, try cleaning and rebuilding your project.