Getting started Eclipse with Android

There’s a lot to get excited about in mobile application development today. With increasingly sophisticated hardware, tablet PCs and a variety of software platforms (Symbian OS, iOS, WebOS, Windows Phone 7…), the landscape for mobile developers is full of opportunities — and a little complex as well.

So much choice can be overwhelming when you just want to get started building mobile applications. Which platform should you choose? What programming language should you learn? What kit do you need for your planned project? In this tutorial, you’ll learn how to start writing applications forAndroid, the open-source mobile operating system popularized by Google.

Why Develop for Android?

Android is an open-source platform based on the Linux kernel, and is installed onthousands of devices from a wide range of manufacturers. Android exposes your application to all sorts of hardware that you’ll find in modern mobile devices — digital compasses, video cameras, GPS, orientation sensors, and more.

Android’s free development tools make it possible for you to start writing software at little or no cost. When you’re ready to show off your application to the world, you can publish it to Google’s Android Market. Publishing to Android Market incurs a one-off registration fee (US $25 at the time of writing) and, unlike Apple’s App Store which famously reviews each submission, makes your application available for customers to download and buy after a quick review process — unless the application is blatantly illegal.

Here are a few other advantages Android offers you as a developer:

• The Android SDK is available for Windows, Mac and Linux, so you don’t need to pay for new hardware to start writing applications.
• An SDK built on Java. If you’re familiar with the Java programming language, you’re already halfway there.
• By distributing your application on Android Market, it’s available to hundreds of thousands of users instantly. You’re not just limited to one store, because there are alternatives, too. For instance, you can release your application on your own blog. Amazon have recently been rumoured to be preparing their own Android app store also.
• As well as the technical SDK documentation, new resources are being published for Android developers as the platform gains popularity among both users and developers.

Enough with the talk — let’s get started developing for Android!

Installing Eclipse and the Android SDK

The recommended environment for developing Android applications is Eclipse with the Android Development Toolkit (ADT) plugin installed. I’ll summarize the process here. If you need more detail, Google’s own developer pages do a good job of explaining the installation and configuration process.

• Download the Android SDK for your platform (Windows, Mac OS X, or Linux).
• Extract the downloaded file to somewhere memorable on your hard drive (on Linux, I use /opt/local/).
• If you don’t already have Eclipse installed, download and install the Eclipse IDE for Java Developers package. For programming, Google recommends using Eclipse 3.5 (Galileo).
• Run Eclipse and choose Help->Install New Software.
• Click Add in the Available Software window.
• Enter Android Development Tools in the Name field, and https://dl-ssl.google.com/android/eclipse/ in the Location field.
• Click OK and check Developer Tools in the list of available software. This will install the Android Development Tools and DDMS, Android’s debugging tool.

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• Click Next and Finish to install the plugin. You’ll need to restart Eclipse once everything is installed.
• When Eclipse restarts, choose Window->Preferences and you should seeAndroid listed in the categories.
• You now need to tell Eclipse where you’ve installed the Android SDK. ClickAndroid and then Browse to select the location where you extracted the SDK files. For example, /opt/local/android-sdk.
  
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• Click OK to have Eclipse save the location of your SDK.

Targeting Android Platforms

Before you can start writing applications for Android, you need to download the SDK platforms for the Android devices for which you want to develop apps. Each platform has a different version of the Android SDK that may be installed on users’ devices. For versions of Android 1.5 and above, there are two platforms available: Android Open Source Project and Google.

The Android Open Source Project platforms are open source, but do not include Google’s proprietary extensions such as Google Maps. If you choose not to use the Google APIs, Google’s mapping functionality won’t be available to your application. Unless you have a specific reason not to, I’d recommended you to target one of the Google platforms, as this will allow you to take advantage of Google’s proprietary extensions.

• Choose Window->Android SDK and AVD Manager.
• Click Available Packages in the left column and check the repository to show a list of the available Android platforms.
• You can choose which platforms to download from the list, or leave everything checked to download all the available platforms. When you’re done, clickInstall Selected and follow the installation instructions.
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Once everything has been successfully downloaded, you’re ready to start developing for Android.

Creating a New Android Project

Eclipse’s New Project Wizard can create a new Android application for you, generating files and code that are ready to run right out of the box. It’s a quick way to see something working, and a good starting point from which to develop your own applications:

• Choose File->New->Project…
• Choose Android Project
• In the New Project dialog, enter the following settings:

  1	Project Name: BrewClock

  2	Build Target: Google Inc. 1.6 (Api Level 4)

  3	Application Name: BrewClock

  4	Package Name: com.example.brewclock

  5	Create Activity: BrewClockActivity

  6	Min SDK Version: 4

  

After clicking Finish, Eclipse will create a new Android project that’s ready to run. Notice you told Eclipse to generate an Activity called BrewClockActivity? This is the code that Android actually uses to run your application. The generated code will display a simple ‘Hello World’ style message when the application runs.

PACKAGES

The package name is an identifier for your application. When the time comes and you are willing to publish on Android Market, it’s exactly this identifier that will be used to track your application for updates, so it’s important to make sure it’s unique. Although we’re using the com.example.brewclock namespace here, for a real application it’s best to choose something likecom.yourcompanyname.yourapplication.

SDK VERSIONS

The Min SDK Version is the earliest version of Android on which your application will run. With each new release of Android, the SDK adds and changes methods. By choosing an SDK version, Android (and the Android Market) knows that your application will only run on devices with a version of Android later or equal than the specified version.

Running Your Application

Now let’s try running the application in Eclipse. As this is the first run, Eclipse will ask what type of project you are working on:

• Choose Run->Run or press Ctrl+F11.
• Choose Android Application and click OK.

Eclipse will now try to run the application on an Android device. At the moment, though, you don’t have any Android devices running, so the run will fail and you’ll be asked to create a new Android Virtual Device (AVD).

ANDROID VIRTUAL DEVICES

An Android Virtual Device (AVD) is an emulator that simulates a real-world Android device, such as a mobile phone or Tablet PC. You can use AVDs to test how your application performs on a wide variety of Android devices, without having to buy every gadget on the market.

You can create as many AVDs as you like, each set up with different versions of the Android Platform. For each AVD you create, you can configure various hardware properties such as whether it has a physical keyboard, GPS support, the camera resolution, and so on.

Before you can run your application, you need to create your first AVD running the target SDK platform (Google APIs 1.6).

Let’s do that now:

• If you haven’t tried to run your application yet, click Run now (or hit Ctrl+F11)
• When the target device warning pops up, click Yes to create a new AVD.
• Click New in the Android SDK and AVD Manager dialog that appears.
• Enter the following settings for the AVD:

  1	Name: Android_1.6

  2	Target: Google APIs (Google Inc.) - API Level 4

  3	SD Card Size: 16 MiB

  4	Skin Built In: Default (HVGA)

• Click Create AVD to have Android build your new AVD.
• Close the Android SDK and AVD Manager dialog.

RUNNING THE CODE

Try running your application again (Ctrl+F11). Eclipse will now build your project and launch the new AVD. Remember, the AVD emulates a complete Android system, so you’ll even need to sit through the slow boot process just like a real device. For this reason, once the AVD is up and running, it’s best not to close it down until you’ve finished developing for the day.

When the emulator has booted, Eclipse automatically installs and runs your application: