问题
Why do projects disappear from the project explorer in Oxygen? I can see them briefly after starting Eclipse but then they disappear.
They can't be re-added or imported because it says they already exist.
I re-cloned the project from git into a different directory, deleted .classpath, .settings and .project and tried to import as a file system but can't advance. The next button is greyed out.
Import projects from folder or archive allowed me to import my clone but then it dissappears again. I know it's there because if I select build, I see my newly added project and other projects that have disappeared.
回答1:
Probably, the projects are only hidden by the active Working Set or by Focus on Active Task.
来源：https://stackoverflow.com/questions/45279599/eclipse-oxygen-projects-disappear