why this eclipse error showing and what should be the solution for it

Question

Missing library: xdoclet-1.2.1.jar. Select the home directory for XDoclet. 1.2.1

why this eclipse error showing and what should be the solution for it alz

Answer 1

It is causing possibly because that jar is not added to your project build path. Follow this steps:

Right click on project(in the package explorer) 
-> Buid Path 
-> Configure Build Path 
-> Java Build Path
-> Libraries tab
-> Add JARs button

Then locate the folder where the jar resides. You can filter your search by typing *.jar in the search field. And then click ok.

Answer 2

I downloaded the xdoclet-lib-1.2.3.zip file from: http://sourceforge.net/projects/xdoclet/files/xdoclet/1.2.3/ unziped it to its folder name, xdoclet-1.2.3, and then from the Eclipse (I was using 4.5) preferences JavaEE -> XDoclet tab selected the Version 1.2.3 and then the Browse button to the xdoclet-1.2.3 folder. Apply and OK and Eclipse error goes away.

Saying all that, I suspect you don't really need it unless you know that you are using xdoclet. If that's the case and it was intentionally left out then the error message should be fixed in Eclipse. I only went around fixing it because of the message.