Скачать или смотреть Understanding Where Android SDK Sources Are Included in Your App Build Process

Discover the ins and outs of Android SDK sources, focusing on how they are included during app builds and the role of android.jar. Learn about the compile and target SDK versions to enhance your development process.
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Understanding Where Android SDK Sources Are Included in Your App Build Process

When you're developing an Android app, understanding the role of the Android SDK and how its sources are included is fundamental to your building process. You might ask, where exactly are the Android SDK sources included when you compile your app? This question delves into the specifics of versioning and the build process, which can be quite confusing for many developers. In this post, we will clarify these concepts to help you streamline your app development journey.

The Build Process Explained

When you build an app, two critical elements come into play: targetSdkVersion and compileSdkVersion. Understanding how these values interact with Android SDK sources is essential.

targetSdkVersion: This defines the highest API level that your app has been tested against. Setting this helps the Android system to adjust compatibility behaviors as the OS evolves.

compileSdkVersion: This value determines the Android API level that your app compiles against. The android.jar file used in your build process reflects this version.

Given a scenario where you have targetSdkVersion 30 and compileSdkVersion 31, you might be left wondering which API level sources are included. The answer is that the sources included are based on the compileSdkVersion, which in this case is 31.

Where Are the SDK Sources Included?

The crucial takeaway is that there are no Android sources directly included in the APK during the build process. Instead, the process utilizes a stubbed version of the API found in a file called android.jar. Here’s how it works:

Stub Implementations: The android.jar file contains stub versions of Android APIs, which serve as placeholders for your build. These stubs are sufficient for compiling your application, as they contain the necessary method definitions and structure.

No Source in APK: When you compile your app, the resulting APK (Android Package) does not contain any source code. Instead, it holds binary code that the device can interpret at runtime.

Real Implementations on Devices: The actual implementations of these APIs are found on the Android device or emulator where your app runs. This separation allows Android devices to execute your compiled code using the APIs defined in the respective Android version's libraries.

In Summary

The sources included during build depend on compileSdkVersion, which determines the stub files used from android.jar.

APKs do not contain Android SDK source code, but rather binary references.

The real API implementations reside on devices or emulators, ensuring that your app interacts properly with the underlying system.

Final Thoughts

Understanding where Android SDK sources are included and how they function within the app build process is crucial for productive development. By distinguishing between targetSdkVersion, compileSdkVersion, and the role of android.jar, you can ensure that your app behaves correctly on different versions of the Android operating system.

If you keep these principles in mind, not only will your development workflow be more efficient, but it will also help you produce robust, compatible applications that deliver great user experiences.