[java] Eclipse error: "Editor does not contain a main type"

Try closing and reopening the file, then press Ctrl+F11.

Verify that the name of the file you are running is the same as the name of the project you are working in, and that the name of the public class in that file is the same as the name of the project you are working in as well.

Otherwise, restart Eclipse. Let me know if this solves the problem! Otherwise, comment, and I'll try and help.