Eclipse is looking for eclipse projects, meaning its is searching for eclipse-specific files in the root directory, namely .project and .classpath. You either gave Eclipse the wrong directory (if you are importing a eclipse project) or you actually want to create a new project from existing source(new->java project->create project from existing source). I think you probably want the … Read more
Maybe you have closed the project and configured the project explorer view to filter closed projects. In that case, have a look at Filters in the Project Explorer view. Make sure that closed projects are disabled in the “Filters” view.
I hope you are trying to run the main class in this way, see screenshot: If not, then try this way. If yes, then please make sure that your class you are trying to run has a main method, that is, the same method definition as below: I hope this will help you.