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kotlinlang

Why there are many projects in various VCSs that contain `.idea` folder? Isn't it IDE configs that should not be put into version control?

Some files are project-specific

See <https://intellij-support.jetbrains.com/hc/en-us/articles/206544839>

I usually start out with <https://www.gitignore.io/api/androidstudio>

I've added `.idea` to `.gitignore`, but left `.iml` file

That should work even if all IDE-specific files are excluded, right?

I’m not sure what you mean by “but left `.iml` file”, also I can’t know what files were already checked in before modifying the `.gitignore`

One way to check if your setup works would be to clone the repository to a new directory and try to open it. Simulate a new person joining the project

It works. One do not need any IDEA config files in repository with properly configured build system. IDEA imports its configs from the build system (at least for me it works with Maven)