This page is obsolete. Redirecting to https://developer.android.com/studio/intro/migrate.html
There are two types of Android projects that work in Android Studio:
In Android Studio, we are focusing all of our efforts on the Gradle-based projects, both in terms of feature development and in testing. If you are using Studio, we strongly recommend you use Gradle-based projects. If you prefer IntelliJ projects, you might want to use IntelliJ: The Android support in Studio, including the gradle support, is also all available in IntelliJ.
At this point, migration from IntelliJ classic projects to Gradle-based projects is not automatic, but it is described here:
If you happen to have created your IntelliJ project by importing an Eclipse project, you should just export your Eclipse project directly to Gradle first, as described here:
Gradle based projects offer significant features for Android development.
There are many more; see the user guide for details.