好吧，鉴于 J2EE 的原始报告仍然开放:https://bugs.eclipse.org/bugs/show_bug.cgi?id=351764 我不认为这可以在 PyDev 端修复(虽然它使问题出现，应该在 J2EE 端修复).

请注意，如果有人想看一下，在 PyDev 方面，这发生在:https://github.com/fabioz/Pydev/blob/development/plugins/org.python.pydev/src_navigator/org/python/pydev/navigator/PythonModelProvider.java，但它是使用适当的 API 完成的(使用 IPipelinedTreeContentProvider)，我目前确信问题不在于 PyDev 方面(尽管如果我被证明错了，我很乐意修复它).

一种解决方法是仅在资源管理器级别禁用 PyDev 或 J2EE(取决于您使用更多的内容)(即:在资源管理器中执行 Ctrl+F10、自定义视图、内容、禁用 PyDev 导航器内容或与 J2EE 相关的内容).

I just installed the latest PyDev 4.4.0 plugin to my Eclipse Mars.1. I created a new Java project in a new workspace. And I add the project to a workingset. In the Eclipse JavaEE perspective, the project has duplicated show in the Project Explorer view when I show workingset as the top level element:

I uninstalled PyDev, now the project show is OK.

Anyone knows the root cause? Or a workaround?

Ref:

A possibly related link: Projects appearing twice in working sets - eclipse

A related Eclipse bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=373031

A related J2EE tooling bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=351764

Well, given that the original report on J2EE is still open: https://bugs.eclipse.org/bugs/show_bug.cgi?id=351764 I don't think this can be fixed at the PyDev side (although it makes the problem appear, it should be fixed on the J2EE side).

As a note, if anyone wants to take a look, on the PyDev side, this happens at: https://github.com/fabioz/Pydev/blob/development/plugins/org.python.pydev/src_navigator/org/python/pydev/navigator/PythonModelProvider.java, but it's done with the proper APIs (using IPipelinedTreeContentProvider), and I'm currently convinced the issue doesn't lie on the PyDev side (although if I'm proved wrong, I'd be happy to fix it).

A workaround would be disabling PyDev or J2EE (depending on which kind of content you use more) just at the explorer level (i.e.: in the explorer do Ctrl+F10, Customize View, Content, disable the PyDev Navigator Content or the Content related to J2EE).