Installing the andriod SDK

Installing the SDK

In this document

1. 1. Preparing Your Development Computer
2. 2. Downloading the SDK Starter Package
3. 3. Installing the ADT Plugin for Eclipse
4. 4. Adding Platforms and Other Packages
   1. Available Packages
   2. Recommended Packages
5. 5. Exploring the SDK (Optional)
6. Next Steps
7. Troubleshooting

See also

1. ADT Plugin for Eclipse
2. Adding SDK Packages

This page describes how to install the Android SDK and set up your development environment for the first time.
If you encounter any problems during installation, see the Troubleshooting section at the bottom of this page.

Updating?

If you already have an Android SDK, use the Android SDK Manager tool to install updated tools and new Android platforms into your existing environment. For information about how to do that, see Adding SDK Packages.

Step 1. Preparing Your Development Computer

Before getting started with the Android SDK, take a moment to confirm that your development computer meets the System Requirements. In particular, you might need to install the JDK, if you don't have it already.
If you will be developing in Eclipse with the Android Development Tools (ADT) Plugin—the recommended path if you are new to Android—make sure that you have a suitable version of Eclipse installed on your computer as described in the System Requirements document. If you need to install Eclipse, you can download it from this location:

http://www.eclipse.org/downloads/

The "Eclipse Classic" version is recommended. Otherwise, a Java or RCP version of Eclipse is recommended.

Step 2. Downloading the SDK Starter Package

The SDK starter package is not a full development environment—it includes only the core SDK Tools, which you can use to download the rest of the SDK packages (such as the latest Android platform).
If you haven't already, get the latest version of the SDK starter package from the SDK download page.
If you downloaded a .zip or .tgz package (instead of the SDK installer), unpack it to a safe location on your machine. By default, the SDK files are unpacked into a directory named android-sdk-<machine-platform>.
If you downloaded the Windows installer (.exe file), run it now and it will check whether the proper Java SE Development Kit (JDK) is installed (installing it, if necessary), then install the SDK Tools into a default location (which you can modify).
Make a note of the name and location of the SDK directory on your system—you will need to refer to the SDK directory later, when setting up the ADT plugin and when using the SDK tools from the command line.

Step 3. Installing the ADT Plugin for Eclipse

Android offers a custom plugin for the Eclipse IDE, called Android Development Tools (ADT), that is designed to give you a powerful, integrated environment in which to build Android applications. It extends the capabilites of Eclipse to let you quickly set up new Android projects, create an application UI, debug your applications using the Android SDK tools, and even export signed (or unsigned) APKs in order to distribute your application. In general, developing in Eclipse with ADT is a highly recommended approach and is the fastest way to get started with Android.
If you'd like to use ADT for developing Android applications, install it now. Read Installing the ADT Plugin for step-by-step installation instructions, then return here to continue the last step in setting up your Android SDK.
If you prefer to work in a different IDE, you do not need to install Eclipse or ADT. Instead, you can directly use the SDK tools to build and debug your application. The Introduction to Android application development outlines the major steps that you need to complete when developing in Eclipse or other IDEs.

Step 4. Adding Platforms and Other Packages

The last step in setting up your SDK is using the Android SDK Manager (a tool included in the SDK starter package) to download essential SDK packages into your development environment.
The SDK uses a modular structure that separates the major parts of the SDK—Android platform versions, add-ons, tools, samples, and documentation—into a set of separately installable packages. The SDK starter package, which you've already downloaded, includes only a single package: the latest version of the SDK Tools. To develop an Android application, you also need to download at least one Android platform and the associated platform tools. You can add other packages and platforms as well, which is highly recommended.
If you used the Windows installer, when you complete the installation wizard, it will launch the Android SDK Manager with a default set of platforms and other packages selected for you to install. Simply click Install to accept the recommended set of packages and install them. You can then skip to Step 5, but we recommend you first read the section about the Available Packages to better understand the packages available from the Android SDK Manager.
You can launch the Android SDK Manager in one of the following ways:

• From within Eclipse, select Window > Android SDK Manager.
• On Windows, double-click the SDK Manager.exe file at the root of the Android SDK directory.
• On Mac or Linux, open a terminal and navigate to the tools/ directory in the Android SDK, then execute:

  android

To download packages, use the graphical UI of the Android SDK Manager to browse the SDK repository and select new or updated packages (see figure 1). The Android SDK Manager installs the selected packages in your SDK environment. For information about which packages you should download, see Recommended Packages.

Figure 1. The Android SDK Manager's Available Packages panel, which shows the SDK packages that are available for you to download into your environment.

Available Packages

By default, there are two repositories of packages for your SDK: Android Repository and Third party Add-ons.
The Android Repository offers these types of packages:

• SDK Tools — Contains tools for debugging and testing your application and other utility tools. These tools are installed with the Android SDK starter package and receive periodic updates. You can access these tools in the <sdk>/tools/ directory of your SDK. To learn more about them, see SDK Tools in the developer guide.
• SDK Platform-tools — Contains platform-dependent tools for developing and debugging your application. These tools support the latest features of the Android platform and are typically updated only when a new platform becomes available. You can access these tools in the <sdk>/platform-tools/ directory. To learn more about them, see Platform Tools in the developer guide.
• Android platforms — An SDK platform is available for every production Android platform deployable to Android-powered devices. Each SDK platform package includes a fully compliant Android library, system image, sample code, and emulator skins. To learn more about a specific platform, see the list of platforms that appears under the section "Downloadable SDK Packages" on the left part of this page.
• USB Driver for Windows (Windows only) — Contains driver files that you can install on your Windows computer, so that you can run and debug your applications on an actual device. You do not need the USB driver unless you plan to debug your application on an actual Android-powered device. If you develop on Mac OS X or Linux, you do not need a special driver to debug your application on an Android-powered device. See Using Hardware Devices for more information about developing on a real device.
• Samples — Contains the sample code and apps available for each Android development platform. If you are just getting started with Android development, make sure to download the samples to your SDK.
• Documentation — Contains a local copy of the latest multiversion documentation for the Android framework API.

The Third party Add-ons provide packages that allow you to create a development environment using a specific Android external library (such as the Google Maps library) or a customized (but fully compliant) Android system image. You can add additional Add-on repositories by clicking Add Add-on Site.

Recommended Packages

The SDK repository contains a range of packages that you can download. Use the table below to determine which packages you need, based on whether you want to set up a basic, recommended, or full development environment:

Environment	SDK Package	Comments
Basic	SDK Tools	If you've just installed the SDK starter package, then you already have the latest version of this package. The SDK Tools package is required to develop an Android application. Make sure you keep this up to date.
	SDK Platform-tools	This includes more tools that are required for application development. These tools are platform-dependent and typically update only when a new SDK platform is made available, in order to support new features in the platform. These tools are always backward compatible with older platforms, but you must be sure that you have the latest version of these tools when you install a new SDK platform.
	SDK platform	You need to download at least one platform into your environment, so that you will be able to compile your application and set up an Android Virtual Device (AVD) to run it on (in the emulator). To start with, just download the latest version of the platform. Later, if you plan to publish your application, you will want to download other platforms as well, so that you can test your application on the full range of Android platform versions that your application supports.
+
Recommended (plus Basic)	Documentation	The Documentation package is useful because it lets you work offline and also look up API reference information from inside Eclipse.
	Samples	The Samples packages give you source code that you can use to learn about Android, load as a project and run, or reuse in your own app. Note that multiple samples packages are available — one for each Android platform version. When you are choosing a samples package to download, select the one whose API Level matches the API Level of the Android platform that you plan to use.
	Usb Driver	The Usb Driver package is needed only if you are developing on Windows and have an Android-powered device on which you want to install your application for debugging and testing. For Mac OS X and Linux platforms, no special driver is needed.
+
Full (plus Recommended)	Google APIs	The Google APIs add-on gives your application access to the Maps external library, which makes it easy to display and manipulate Maps data in your application.
	Additional SDK Platforms	If you plan to publish your application, you will want to download additional platforms corresponding to the Android platform versions on which you want the application to run. The recommended approach is to compile your application against the lowest version you want to support, but test it against higher versions that you intend the application to run on. You can test your applications on different platforms by running in an Android Virtual Device (AVD) on the Android emulator.

Once you've installed at least the basic configuration of SDK packages, you're ready to start developing Android apps. The next section describes the contents of the Android SDK to familiarize you with the packages you've just installed.
For more information about using the Android SDK Manager, see the Adding SDK Packages document.

Step 5. Exploring the SDK (Optional)

Once you've installed the SDK and downloaded the platforms, documentation, and add-ons that you need, we suggest that you open the SDK directory and take a look at what's inside.
The table below describes the full SDK directory contents, with packages installed.

Name			Description
add-ons/			Contains add-ons to the Android SDK development environment, which let you develop against external libraries that are available on some devices.
docs/			A full set of documentation in HTML format, including the Developer's Guide, API Reference, and other information. To read the documentation, load the file offline.html in a web browser.
platform-tools/			Contains platform-dependent development tools that may be updated with each platform release. The platform tools include the Android Debug Bridge (adb) as well as other tools that you don't typically use directly. These tools are separate from the development tools in the tools/ directory because these tools may be updated in order to support new features in the latest Android platform.
platforms/			Contains a set of Android platform versions that you can develop applications against, each in a separate directory.
	<platform>/		Platform version directory, for example "android-11". All platform version directories contain a similar set of files and subdirectory structure. Each platform directory also includes the Android library (android.jar) that is used to compile applications against the platform version.
samples/			Sample code and apps that are specific to platform version.
tools/			Contains the set of development and profiling tools that are platform-independent, such as the emulator, the Android SDK Manager, the AVD Manager, ddms, hierarchyviewer and more. The tools in this directory may be updated at any time using the Android SDK Manager and are independent of platform releases.
SDK Readme.txt			A file that explains how to perform the initial setup of your SDK, including how to launch the Android SDK Manager tool on all platforms.
SDK Manager.exe			Windows SDK only. A shortcut that launches the Android SDK Manager tool, which you use to add packages to your SDK.

Optionally, you might want to add the location of the SDK's tools/ and platform-tools to your PATH environment variable, to provide easy access to the tools.

How to update your PATH

Next Steps

Once you have completed installation, you are ready to begin developing applications. Here are a few ways you can get started:
Set up the Hello World application

• If you have just installed the SDK for the first time, go to the Hello World tutorial. The tutorial takes you step-by-step through the process of setting up your first Android project, including setting up an Android Virtual Device (AVD) on which to run the application.

Following the Hello World tutorial is an essential first step in getting started with Android development.

Learn about Android

• Take a look at the Dev Guide and the types of information it provides.
• Read an introduction to Android as a platform in What is Android?
• Learn about the Android framework and how applications run on it in Application Fundamentals.
• Take a look at the Android framework API specification in the Reference tab.

Explore the development tools

• Get an overview of the development tools that are available to you.
• Read the Introduction to Android application development.
• Read Using Hardware Devices to learn how to set up an Android-powered device so you can run and test your application.

Follow the Notepad tutorial

• The Notepad Tutorial shows you how to build a full Android application and provides helpful commentary on the Android system and API. The Notepad tutorial helps you bring together the important design and architectural concepts in a moderately complex application.

Following the Notepad tutorial is an excellent second step in getting started with Android development.

Explore some code

• The Android SDK includes sample code and applications for each platform version. You can browse the samples in the Resources tab or download them into your SDK using the Android SDK Manager. Once you've downloaded the samples, you'll find them in <sdk>/samples/<platform>/.

Visit the Android developer groups

• Take a look at the Community pages to see a list of Android developers groups. In particular, you might want to look at the Android Developers group to get a sense for what the Android developer community is like.

Troubleshooting

Ubuntu Linux Notes

• If you need help installing and configuring Java on your development machine, you might find these resources helpful:
  • https://help.ubuntu.com/community/Java
  • https://help.ubuntu.com/community/JavaInstallation
• Here are the steps to install Java and Eclipse, prior to installing the Android SDK and ADT Plugin.
  1. If you are running a 64-bit distribution on your development machine, you need to install the ia32-libs package using apt-get::

     apt-get install ia32-libs

  2. Next, install Java:

     apt-get install sun-java6-jdk

  3. The Ubuntu package manager does not currently offer an Eclipse 3.3 version for download, so we recommend that you download Eclipse from eclipse.org (http://www.eclipse.org/ downloads/). A Java or RCP version of Eclipse is recommended.
  4. Follow the steps given in previous sections to install the SDK and the ADT plugin.

Other Linux Notes

• If JDK is already installed on your development computer, please take a moment to make sure that it meets the version requirements listed in the System Requirements. In particular, note that some Linux distributions may include JDK 1.4 or Gnu Compiler for Java, both of which are not supported for Android development.

Andriod begginers tutorials

Introduction

This tutorial is a starting point for developing Android apps. It will explain the very basics of the Android SDK (Software Development Kit) and how to use it with Eclipse. To understand this tutorial, you don't need to have any knowledge about programming in Java, but it might be helpful for further programming to understand the basics of object orientated programming. This tutorial explains Android beginners how to create an Android Project in Eclipse, work with resources, and create some first code.

Setup Eclipse and the Android SDK

If you don't already have a running environment to develop Android apps, follow the instructions at this link.
Hint: PATH means the Path Environment Variable. In Windows, you will find it under "Control Panel/System/Advanced System Settings/Environment Variables" in the lower list box. You can check what version of Java is installed, by going in the command line and typing java -version.

Let's Get Started

Now we want to create our first application, which is (as always) a Hello World application. First of all, start Eclipse. Then select "File/New/Project". In the "New Project" dialog, select "Android/Android Project" and click "Next".

Here you can set up the project. First of all, we need to give the project a name, so type "Hello World" in the name box. Next you have to select the Android version you want to use. Here we choose version 2.2. As we see in the last column, we need the API Version 8 for this Android version, so we type an "8" in the Min SDK Version box. Also, the project requires an application name. (Notice that this name is also used in code, so the name should have no whitespaces). Usually, you use the project name and delete all whitespaces (e.g., "helloworld" for this project). Next, you have to define the package of the project. We will use "com.test.helloworld" here (a package can group multiple classes; for more information, see here). At least, you need a name for the activity (one App might have multiple Activities; they are like a single part/screen of the app). In this example, we simply use "HelloWorldApp".

Before we can finally start our first project, we need to create a configuration. This configuration specifies under which circumstances the app will be started. E.g., you can control the network speed the emulator/app can use. Also, you can choose different emulators to test the app with different versions of Android or in different screen sizes. To create the configuration, go to "Run/Run Configurations". Now click the "Android Application" tab at the side and then the New button above the tabs. Call the new configuration "HelloWorldConfig" and select our project over the Browse button. Now move on to the target tab. Here you can select the network speed and which emulator will be used.

Since we haven't created an emulator till now, we need to do that first. Click the automatic control to enable the buttons at the side and then click on the manager-button. Here, click the new button to the right to create a new emulator. In the following screen, you can enter a name for the emulator (I have used "DefaultAndroidEmulator") and specify the details (like Android version, SD card size, and much more). You can control every little detail of the emulator over the hardware section.

Once you are done with that, click "Create AVD" and close the manager window. Now we have successfully created the run configurations. Click "Apply" and close the configurations. At least run your first Android project.
Notice: It may take the emulator some time to get started, so be patient! Also, I have cropped the image so that you can't see the keyboard or the D-pad.
Congratulations! You just created your first App!

Coding is Fun

After we have set up everything, it's (finally) time to actually getting started with the code, because we all know: Coding is fun!
But before we can actually jump into the Java code, we need to understand the structure of an Android Application. Go to your Package Explorer and enlarge the "Hello World" project. You will see five folders and two files. Let's get started with the one of these two files, the AndroidManifest file. This file contains all the information about your project, like the icon, the name of the author. To open it, make a right click on it and choose "Open With/Android Manifest Editor". In the upcoming tab, you can specify the package name and the version of your project. At the bottom, you will find additional tabs. I think most of the settings you will find are pretty much self-explanatory. Note the @ in front of some attributes. This shows that the following string is a reference to a resource. You can find the resources in the "res" folder of your project. If you enlarge it, you will notice that it has some subfolders. To be specific, the res folder can have seven types of subfolders: values, drawable, layout, animations, xml, styles, and raw.
Let's focus on the values folder first. Here you can store all kinds of simple resources (like strings, colors, numbers, dimensions, arrays, etc.). By default, you will find the strings.xml file in there. When you open it (with right click, "Open with/Android Layout Editor"), you will see that it contains two values. The first is the message you see when you run your project, and the second is the name of your app. You can add new values if you want to use them later on in code (or in the Manifest or Layout files). You can also create specific resources using quantifiers. If you add a - to the folder's name, you can add a quantifier to the name. E.g., you can rename the values folder to values-en which means that the content of the folder is only used by Android phones with English language activated. If you do not add a quantifier, the resources are default. The default resources are used if no specific resources for the current system are found. If the project is started, all resources will be compiled as efficiently as possible and added to the package. Also, a reference will be created (called R) which allows you to access the resources in code. Since this is only a tutorial, I will not focus on all the types of resources here. You can find more information on resources and quantifiers here.
At last, it is time to start coding! Go to the "src" folder. In the folder, you will find the package folder, open the HelloWorld.java file. You will see the default code for an Android Activity:

package com.test.helloworld; //the package we are working in

//some android packages we need to import
import android.app.Activity;
import android.os.Bundle;

//our activity class (extendes the default activity class)
public class HelloWorldApp extends Activity {
    /** Called when the activity is first created. */
    @Override
    //the function called when activity is created
    public void onCreate(Bundle savedInstanceState) {
        //call the create fct. Of the base class
        super.onCreate(savedInstanceState);
        //load the layout specified in the layout.xml
        setContentView(R.layout.main);
    }
}

As you can see, we create a new activity by extending the default Android activity class. Then we override the default onCreate function, which is called when the project is created. In there, we load our own layout from the resources and also call the onCreate function of the base class. Now let's take a closer look at the layout file. You find it in the layout folder under resources. When you open it, it should look like this:

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<linearlayout android:layout_height="fill_parent" 
    android:layout_width="fill_parent" android:orientation="vertical" 
    xmlns:android="http://schemas.android.com/apk/res/android" />
      <textview android:layout_height="wrap_content" 
        android:layout_width="fill_parent" android:text="@string/hello" />
</linearlayout />

You see the root node is called LinearLayout. As you you might already have figured out, there are different types of layouts:

• FrameLayout: All controls (children) are placed in the upper left corner.
• LinearLayout: All children are positioned in vertical/horizontal order.
• RelativeLayout: The positions of the children are specified in relation to the other children.
• TableLayout: The child elements are placed with a grid.
• AbsoluteLayout: The child elements are positioned based on absolute coordinates (in pixel).

Once you have chosen a layout type, you can add child elements. In the code given, there is already a TextView, which is used to display text on the screen. The current content is a reference to a resource defined in the values.xml file. As you will see, it uses the whole width of the screen, but is only as long as it needs to, to display the content. We might start with some small changes. Let's change the text color of the TextView to green:

<textview android:layout_height="wrap_content" 
    android:layout_width="fill_parent" android:text="@string/hello" 
    android:textcolor="#FF00FF00" />

Now, launch the project and see the changes. Next, let's add a new control called EditText:

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<linearlayout android:layout_height="fill_parent" 
     android:layout_width="fill_parent" android:orientation="vertical" 
     xmlns:android="http://schemas.android.com/apk/res/android" />
        <edittext android:layout_height="wrap_content" 
             android:layout_width="fill_parent" android:textcolor="#FF0000FF"
             android:id="@+id/et_Text" />
<textview android:layout_height="wrap_content" android:layout_width="fill_parent"
    android:textcolor="#FF00FF00" android:id="@+id/lv_View" />
</linearlayout />

When we want to access the controls in code, they need to have an ID. Next we create some code for the controls. Go to the helloworld.java file.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    //loading the layout over the resource reference
    setContentView(R.layout.main);
        
    //get the two controls we created earlier, also with the resource reference and the id
    final TextView tv_View = (TextView)findViewById(R.id.tv_View);
    final EditText et_Text = (EditText)findViewById(R.id.et_Text);
        
    //add new KeyListener Callback (to record key input)
    et_Text.setOnKeyListener(new OnKeyListener()
    {
        //function to invoke when a key is pressed
        public boolean onKey(View v, int keyCode, KeyEvent event)
        {
            //check if there is 
            if (event.getAction() == KeyEvent.ACTION_DOWN)
            {
                //check if the right key was pressed
                if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER)
                {
                                    //add the text to the textview
                    tv_View.setText(tv_View.getText() + ", " + 
                                     et_Text.getText());
                                    //and clear the EditText control
                    et_Text.setText("");
                    return true;
                }
            }
            return false;
        }
    });
}

We will analyze the code line by line. First of all, as before, we load the layout. Then we create a TextView and a EditText variable and load our interface objects in them (that's what we need the ID for). Finally, we add a new OnKeyListener to the EditText control. In this OnKeyListener, we create the method onKey, which is called when a key is pressed, when the control is active. In the method, we perform two checks: the first to be sure that a key is pressed down (and not released), and the second to specify the key (in this case, the center key of the D-pad). If both checks are passed, we add the text of the EditText control to the TextView, and finally the text of the EditText control is deleted. Run and test the application. Great, you created your first real Android app.

Android App Design

As with every platform, Android has its own design challenges. Always keep in mind that you are developing for a mobile platform with limited memory, disk space, and processing power. Therefore, Android automatically kills processes (each app runs in its own process) to keep the system responsive. Processes are sorted after importance. The most important is the currently active process, followed by visible and stated service processes. The bottommost types of processes in hierarchy are background and empty processes. Keep that in mind when you design your application, because you don't want its process to be killed in the middle of something. Also, you can use whatever hardware is built into the Android phone. But notice that not all phones might have this hardware, and so not all might be able to run your app.