Unsupported Modules Detected: Unfortunately you can't have non-Gradle Java modules and Android-Gradle modules in one project

Question

Unsupported Modules Detected: Compilation is not supported for the following

modules: MemorandamApp. Unfortunately, you can't have non-Gradle Java modules and Android-Gradle modules in one project.

This Error caused me to erase my files. Newly opened files and created files are affected by this problem.

Answer 1

1- close the project

2- close Android Studio IDE

3- delete the .idea directory

4- delete all .iml files

5- open Android Studio IDE and import the project

The answer is taken from HERE