[android] What is the difference between min SDK version/target SDK version vs. compile SDK version?

What are the differences between "min sdk version/target sdk version" and "compile sdk version"? I know what min and target sdk means, but what does compile sdk version mean?

In Eclipse, I have min/max and target sdk, but in android studio there are these three settings.

The formula is

minSdkVersion <= targetSdkVersion <= compileSdkVersion

minSdkVersion - is a marker that defines a minimum Android version on which application will be able to install. Also it is used by Lint to prevent calling API that doesn’t exist. Also it has impact on Build Time. So you can use build flavors to override minSdkVersion to maximum during the development. It will help to make build faster using all improvements that the Android team provides for us. For example some features Java 8 are available only from specific version of minSdkVersion.

targetSdkVersion - If AndroidOS version is >= targetSdkVersion it says Android system to turn on specific(new) behavior changes. *Please note that some of new behaviors will be turned on by default even if thought targetSdkVersion is <, you should read official doc.

For example:

• Starting in Android 6.0 (API level 23) Runtime Permissions were introduced. If you set targetSdkVersion to 22 or lower your application does not ask a user for some permission in run time.

• Starting in Android 8.0 (API level 26), all notifications must be assigned to a channel or it will not appear. On devices running Android 7.1 (API level 25) and lower, users can manage notifications on a per-app basis only (effectively each app only has one channel on Android 7.1 and lower).

• Starting in Android 9 (API level 28), Web-based data directories separated by process. If targetSdkVersion is 28+ and you create several WebView in different processes you will get java.lang.RuntimeException

compileSdkVersion - actually it is SDK Platform version and tells Gradle which Android SDK use to compile. When you want to use new features or debug .java files from Android SDK you should take care of compileSdkVersion. One more example is using AndroidX that forces to use compileSdkVersion - level 28. compileSdkVersion is not included in your APK: it is purely used at compile time. Changing your compileSdkVersion does not change runtime behavior. It can generate for example new compiler warnings/errors. Therefore it is strongly recommended that you always compile with the latest SDK. You’ll get all the benefits of new compilation checks on existing code, avoid newly deprecated APIs, and be ready to use new APIs. One more fact is compileSdkVersion >= Support Library version

You can read more about it here. Also I would recommend you to take a look at the example of migration to Android 8.0.

[buildToolsVersion]

compileSdkVersion : The compileSdkVersion is the version of the API the app is compiled against. This means you can use Android API features included in that version of the API (as well as all previous versions, obviously). If you try and use API 16 features but set compileSdkVersion to 15, you will get a compilation error. If you set compileSdkVersion to 16 you can still run the app on a API 15 device.

minSdkVersion : The min sdk version is the minimum version of the Android operating system required to run your application.

targetSdkVersion : The target sdk version is the version your app is targeted to run on.

The min sdk version is the minimum version of the Android operating system required to run your application.

The target sdk version is the version of Android that your app was created to run on.

The compile sdk version is the the version of Android that the build tools uses to compile and build the application in order to release, run, or debug.

Usually the compile sdk version and the target sdk version are the same.