I have recently returned to a project after not using it for a couple of weeks. The project was not created in Eclipse it was imported, and there is no '.classpath' file in the project workspace.
I am sure that previously I successfully added new .jar files by simply right clicking them and going to 'Add to build path', but thanks to an unrelated error I had to re-add the files to the build path, and now whenever I try to add a new .jar file I get the following error:
Error while adding a library
Reason:
Could not write file C:\Users\Charles\workspace\hive\.classpath
Or, if I try to add a file using Configure build path, I get the following error:
'Setting build path' has encountered a problem.
Could not write file:
C:\Users\Charles\workspace\hive\.classpath
I have earlier versions of this project prior to adding .jar files, and there is no .classpath file for any of them either, so I haven't accidentally deleted it at any point.
If anyone can help me out at all, I'd be ever so grateful (I desperately need to add these .jar files so I can do some actual work).
The thing that annoys me the most is I'm sure it worked before, but I have tried to do the same in earlier versions of the project and I am always getting the same error now.
I had the same problem. I had just setup a new PC, I transferred my projects to the new PC, clicked on the workspace directory, and changed the permission so that I (the 'me' on my new PC) owned all the files in all all sub-directories. However, even after doing this, eclipse couldn't write to the .classpath files. I verified that I could write to them using notepad, and that worked fine. I also verified that the O/S knew I was really the owner, but it didn't help. I also tried running as admin, but that didn't help either.
Then I found this link: http://blog.ryanrampersad.com/2010/03/03/setting-build-path-has-encountered-a-problem-in-eclipse/, which indicates that when you copy files to a windows7 machine, windows may set the 'hidden' attribute on the file, and when this happens, eclipse can't work with it. I did a find files from the workspace directory, looking for '.project' (and subsequently '.classpath'), and selected all the files, right-clicked, and un-checked the 'hidden' attribute. This fixed my problem.
The .classpath file in eclipse is a configuration file (in XML) which stores the project classpath properties. If it can't be written, perhaps it's an access problem. Right-click the file in windows explorer and check under the security tab to see if you have write permissions. You may have to run Eclipse as administrator.
Go to your Project in WorkSpace. And then change your files' attribute from hidden.
Also, then close-open your project and then clean it.
This should work.
Go to the project folder and remove hidden property for the ".classpath" file. Hope this helps. Thanks.
Right click Project >> Source >> Format - worked for me!
The below solution worked for me.
Go to your project folder --> Right click folder --> Properties --> In general tab, Uncheck the attribute(last field), Read-only (Only applies to this folder) option.
Then try adding jars in eclipse.
Hope this helps
Just had the same issue after trying to create my view on a new PC. The cause of the issue for me was that .classpath file was marked as read-only, for whatever reason. To resolve this I did the following:
Go to workspace directory --> Java Source folder --> Project Directory --> right click on .classpath and select Properties from the list --> uncheck 'Read-only' and/or 'Hidden' attribute checkbox(es) --> Click 'Apply' button.
I had a similar problem after changing my project to Gradle. When I right-clicked on javaw.exe->Properties in the 'debug' view, I saw the classpath was (mostly) missing, for instance the 'bin' directory containing the classes wasn't there.
Solution for me was just to delete the 'run debug configuration' and create a new one. After that the classpath was included and I could run it from Eclipse again.
Hope this helps someone out there.
As doc_180 mentioned, the .Classpath would be hidden. Right click > Properties and Unhide the file, you should be ok.
来源：https://stackoverflow.com/questions/4853718/missing-classpath-file-in-eclipse-project