compilation – Eclipse wont compile/run java file

Make a project to put the files in.
- File -> New -> Java Project
- Make note of where that project was created (where your workspace is)
Move your java files into the src folder which is immediately inside the projects folder.
- Find the project INSIDE Eclipses Package Explorer (Window -> Show View -> Package Explorer)
- Double-click on the project, then double-click on the src folder, and finally double-click on one of the java files inside the src folder (they should look familiar!)
Now you can run the files as expected.

Note the hollow J in the image. That indicates that the file is not part of a project.

Hollow

I was also in the same problem, check your build path in eclipse by Right Click on Project > build path > configure build path

Now check for Excluded Files, it should not have your file specified there by any means or by regex.

Cheers!

right click somewhere on the file or in project explorer and choose run as->java application