Question

I use Eclipse to write Java code and use DropBox to sync my code with others’ across our multiple computers. Most of the time, everything works as expected: if anyone makes a change on either end, the change is saved and when the other person refreshes the Eclipse workspace, the changes come through and can be viewed and run successfully.

Sometimes, one of several errors arises. Sometimes Eclipse says it cannot find a main class and sometimes it says it could not find the class itself. Sometimes it will not report an error but for some reason will not actually update the .class file and therefore run an old version even though the compiler displays the new source code and that saves. I’ve then noticed that if I manually copy the code into a new .java file elsewhere in the file system and then compile it, it works fine, but for some reason it refuses to regenerate the .class file and I have to delete it manually and replace it with the one generated in the other project–then it works. But for solving the other problems everything needs to be manually copied, deleted, and re-pasted….

[The actual errors include NoClassDefFoundError, UnsupportedClassVersionError, and some other error related to not having a main class.]

I realize that the description here is somewhat vague, but unfortunately I’m not entirely sure what’s going on. I hope I’m just missing some basic fact that would help solve all these problems.

Thanks!

Answer 1

I’m sure you will see issues using Dropbox for sharing your source.

Eclipse does not know what Dropbox is doing whilst it’s uploading and downloading updates and their activities will certainly not be synchronised. At arbitrary points in time when Eclipse tries to do builds etc. it will find unexpected activity going on, maybe even partially downloaded source files which might explain the specific errors you are seeing.

You’re trying to do something more complex than sharing photos or documents. The advice I would give is to use a source control system like git or subversion for source code sharing and control. You can then make use of plugins for Eclipse that are designed to integrate these systems in an easy to use way. There’s a learning curve there, but the skills will serve you well.

You can use online versions of these solutions like github and unfuddle if you want to consume sharing, backup and version control of source as a service like you do with Dropbox. They’re free, too.