This problem, in most cases, is not caused by error in your codes, it’s more likely a mistake of misplaced Java files. I encountered this problem when I run a Java file using Eclipse for the first time. Previously I was using jCreator to do my Java programming, so I am not used to project-based IDE like Eclipse.

#1 – Syntax of main() Method

First thing to do is of course to check whether your java file DOES really has no main() method to be run. Check the syntax too. If you are sure about your syntax, proceed to next step.

The syntax:

public static void main (String[] args) { 

}

#2 – Check your project source folder / build path

Go to Project > Properties > Java Build Path > Source tab

In most cases, your source folder will be workspace-folder/project-name/src. So, when Eclipse run your Java file, it will look into this folder. So all your Java files should be in this folder!

Now check out your Project Tree. Example below shows my project tree, with 2 Java file.

And this is where i found my problem. My Java files were not placed inside “src” folder so Eclipse is complaining. So drag them into the “src” folder. Eclipse should now stop complaining about the problem.