Android sdk build target

What Is the Android SDK and How to Start Using It

Android SDK is a software development kit developed by Google for the Android platform. The Android SDK allows you to create Android apps, and you don’t need to be an expert to use it. In this tutorial, I’ll explain what the Android SDK is and how to get started with it.

Android SDK comes bundled with Android Studio, Google’s official integrated development environment (IDE) for the Android operating system. You can learn about Android Studio and the Android App Development Kit in another of my articles.

In this post, we’ll look at:

• What is the Android SDK?
• How to install the Android SDK
• What is the Android SDK Manager?
• What are the components of the Android SDK?

What Is the Android SDK?

The Android SDK is a collection of software development tools and libraries required to develop Android applications. Every time Google releases a new version of Android or an update, a corresponding SDK is also released which developers must download and install. It is worth noting that you can also download and use the Android SDK independently of Android Studio, but typically you’ll be working through Android Studio for any Android development.

The Android SDK comprises all the tools necessary to code programs from scratch and even test them. These tools provide a smooth flow of the development process from developing and debugging, through to packaging.

The Android SDK is compatible with Windows, macOS, and Linux, so you can develop on any of those platforms.

How to Install the Android SDK

The Android SDK is optimized for Android Studio, and hence to effectively reap its benefits, you will need to install Android Studio. Having the Android SDK managed from within Android Studio is easier since support for languages like Java, Kotlin, and C++ is handled automatically. Not only that, but updates to the Android SDK are handled automatically by Android Studio.

To install the Android SDK from within Android Studio, first start Android Studio.

• From the Android Studio start page, select Configure > SDK Manager.

• If you already have Android Studio open, the SDK Manager icon is found on the top right corner, as shown below.

Install the required Android SDK platform packages and developer tools. A good start is to install:

• Android SDK Build-Tools
• Android Emulator
• Android SDK Platform-Tools
• Android SDK Tools
• Documentation for Android SDK

Click Apply, and Android Studio will install the selected tools and packages.

What Is the SDK Manager?

The Android SDK is composed of modular packages that you can download, install, and update separately using the Android SDK Manager. The SDK Manager helps to update new SDK releases and updates whenever a new Android platform is released. The SDK manager can be found in the top-right corner of the Android Studio screen, as shown below.

All that is required to follow the instructions provided, and the updates will be immediately downloaded to your environment.

What Are the Components of the Android SDK?

The Android SDK consists of an emulator, development tools, sample projects with source code, and the required libraries to build Android applications. Let’s look at the key components one by one.

Android SDK Tools

Android SDK Tools is a component of the Android SDK. It includes a complete set of development and debugging tools for Android, and is included with Android Studio. The SDK Tools also consist of testing tools and other utilities required to develop an app.

SDK Build Tools

Build tools are required for building components for building the actual binaries for your Android app. Always ensure your build tools component is up to date by downloading the latest version in the Android SDK Manager.

SDK Platform-Tools

Android Platform-Tools are used to support the features for the current Android platform and are necessary for Android app development. These tools interface with the Android platform on the device you use for testing. They include:

• Android Debug Bridge (adb): This is a handy command-line tool that lets you communicate with a device. The adb command allows you to perform device actions, such as installing and debugging apps. It also provides access to a Unix shell that you can use to run a variety of commands on a device.
• fastboot: This lets you flash a device with a new system image.
• systrace: This tool helps collect and inspect timing information across all processes running on your device at the system level. It’s crucial for debugging app performance.

SDK Platform-Tools are backward compatible, so you need only one version of the SDK Platform-Tools.

SDK Platform

For each version of Android, there’s one SDK Platform available. These are numbered according to the Android version (e.g. Android 7 Nougat) and an API version (e.g. API Level 24). Before you build an Android app, you must specify an SDK Platform as your build target. Newer SDK Platform versions have more features for developers, but older devices may not be compatible with the newer platform versions.

Google APIs

Google provides a number of exclusive Google APIs to make developing your app easier. They also offer a system image for the emulator so you can test your app using the Google APIs.

Android Emulator

The Android Emulator is a QEMU-based device-emulation tool that simulates Android devices on your computer, allowing developers to test applications on different devices and Android API levels, without needing to have physical devices for each. The emulator comes with configurations for various Android phones, tablets, Wear OS, and Android TV devices.

The Android emulator provides almost all of the capabilities of a real Android device. You can perform the following activities:

• simulate phone calls and text messages
• simulate different network speeds
• specify the location of the device
• simulate hardware sensors such as rotation
• access Google Play Store and much more

Often it is faster and easier to test your app with an emulator instead of using a physical device.

Conclusion

In this post, we looked at some of the basics of the Android SDK. The Android SDK is the only way to develop for Android devices. Fortunately, it contains extensive documentation, tutorials, samples, best practice guidance, and an array of tools for many different development tasks.

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Android Studio comes with some default templates to help start an app, but these are very basic and provide minimal, generic functionality.

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Take a look at some of our roundups of the best Android app templates:

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Picking your compileSdkVersion, minSdkVersion, and targetSdkVersion

Depending on the time of the year, it might only be a few months after you release an app that a new version of Android is announced. What does that mean for your app though — is everything going to break?

You’ll be happy to know that forward compatibility is a strong focus of Android — existing apps built against prior SDKs should not break when the user updates to a new version of Android. This is where compileSdkVersion, minSdkVersion, and targetSdkVersion come in: they control what APIs are available, what the required API level is, and what compatiblity modes are applied, respectively.

compileSdkVersion

compileSdkVersion is your way to tell Gradle what version of the Android SDK to compile your app with. Using the new Android SDK is a requirement to use any of the new APIs added in that level.

It should be emphasized that changing your compileSdkVersion does not change runtime behavior. While new compiler warnings/errors may be present when changing your compileSdkVersion, your compileSdkVersion is not included in your APK: it is purely used at compile time. (You should really fix those warnings though — they were added for a reason!)

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.

Note that if you use the Support Library, compiling with the latest SDK is a requirement for using the latest Support Library releases. For example, to use the 23.1.1 Support Library, you must have a compileSdkVersion of at least 23 (those first numbers need to match!). In general, a new version of the Support Library is released alongside a new platform version, providing compatibility shims to newly added APIs as well as new features.

minSdkVersion

If compileSdkVersion sets the newest APIs available to you, minSdkVersion is the lower bound for your app. The minSdkVersion is one of the signals the Google Play Store uses to determine which of a user’s devices an app can be installed on.

It also plays an important role during development: by default lint runs against your project, warning you when you use any APIs above your minSdkVersion, helping you avoid the runtime issue of attempting to call an API that doesn’t exist. Checking the system version at runtime is a common technique when using APIs only on newer platform versions.

Keep in mind that libraries you use, such as any of the Support Libraries or Google Play services, may have their own minSdkVersion — your app’s minSdkVersion must be at least as high as your dependencies’ minSdkVersion — if you have libraries that require 4, 7, and 9, your minSdkVersion must be at least 9. In rare cases where you want to continue to use a library with a higher minSdkVersion than your app (and deal with all edge cases/ensure the library is only used on newer platform versions), you can use the tools:overrideLibrary marker, but make sure to test thoroughly!

When deciding on a minSdkVersion, you should consider the stats on the Dashboards, which give you a global look on all devices that visited the Google Play Store in the prior 7 days — that’s your potential audience when putting an app on Google Play. It is ultimately a business decision on whether supporting an additional 3% of devices is worth the development and testing time required to ensure the best experience.

Of course, if a new API is key to your entire app, then that makes the minSdkVersion discussion quite a bit easier. Just remember that even 0.7% of 1.4 billion devices is a lot of devices.

targetSdkVersion

The most interesting of the three, however, is targetSdkVersion. targetSdkVersion is the main way Android provides forward compatibility by not applying behavior changes unless the targetSdkVersion is updated. This allows you to use new APIs (as you did update your compileSdkVersion right?) prior to working through the behavior changes.

Much of the behavior changes that targetSdkVersion implies are documented directly in the VERSION_CODES, but all of the gory details are also listed on the each releases’ platform highlights, nicely linked in the API Levels table.

For example, the Android 6.0 changes talk through how targeting API 23 transitions your app to the runtime permissions model and the Android 4.4 behavior changes detail how targeting API 19 or higher changes how alarms set with set() and setRepeating() work.

With some of the behavior changes being very visible to users (the deprecation of the menu button, runtime permissions, etc), updating to target the latest SDK should be a high priority for every app. That doesn’t mean you have to use every new feature introduced nor should you blindly update your targetSdkVersion without testing — please, please test before updating your targetSdkVersion! Your users will thank you.

Gradle and SDK versions

So setting the correct compileSdkVersion, minSdkVersion, and targetSdkVersion is important. As you might imagine in a world with Gradle and Android Studio, these values are integrated into the tools system through inclusion in your module’s build.gradle file (also available through the Project Structure option in Android Studio):

The compileSdkVersion, being a compile time thing (who would have guessed!), is one of the android settings alongside with your build tools version. The other two are slightly differently in that they are declared at the build variant level — the defaultConfig is the base for all build variants and where’d you put default values for these, but you could imagine a more complicated system where specific versions of your app have a different minSdkVersion for example.

minSdkVersion and targetSdkVersion also differ from compileSdkVersion in that they are included in your final APK — if you were to look at the generated AndroidManifest.xml, you’d see a tag such as:

You’ll find if you manually put this in your manifest, it’ll be ignored when you build with Gradle (although other build systems might certainly rely on it being there).

Putting it all together

If you made it through the bolded notes, you’ll notice a relationship between the three values:

This intuitively makes sense — if compileSdkVersion is your ‘maximum’ and minSdkVersion is your ‘minimum’ then your maximum must be at least as high as your minimum and the target must be somewhere in between.

Ideally, the relationship would look more like this in the steady state:

You’ll hit the biggest audience with a low minSdkVersion and look and act the best by targeting and compiling with the latest SDK — a great way to #BuildBetterApps.

Join the discussion on the Google+ post and follow the Android Development Patterns Collection for more!

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