Dear Learner,

We hope you are doing good.

Please follow the below steps to resolve the issue:

(i) Click on the drop down next to the Run button as shown below:

(ii)  Now click on Run Configuration.

(iii) Click on Java Application as shown below and make sure that the Project and Main Class are selected correctly.

(iv) Now click on Run.

Please feel free to revert if you need any further help.