Creating an eclipse project for android. Setting up Eclipse for Android development. Slow start emulator

In this guide, you will learn how to start developing for Android, namely: mobile applications on Android Eclipse platform + SDK. Today, there are many approaches to developing and building mobile apps for Android. Complex hardware devices, tablet PCs and various software platforms (Symbian OS, iOS, webOS, Windows phone 7…) open up endless space for developers.

So, the list of applications to start developing mobile applications for Android is huge. Which platform to choose? What programming language to learn? Which set of applications to choose for project planning? In this tutorial, you'll learn how to get started developing mobile apps for the Android platform, Google's open source mobile OS.

Why the Android platform?

Android is an open platform based on the Linux kernel. It is installed on thousands of devices from a wide range of manufacturers. Android provides apps for every kind of hardware imaginable today. mobile devices- digital compasses, video cameras, GPS, sensors and more.

Free android development tools let you quickly start creating free or almost free apps. When you're ready to show the world your program, you can publish it through the Android Market. Publishing to the Android Market requires a one-time registration fee ($25 at the time of writing) and, unlike Apple's App Store (which is very strict on eligibility), makes your app available for download and purchase after quick review- if the application does not violate the rules and the law.

Here are a few other Android SDK features that offer you benefits as a developer:

• The Android SDK is available for Windows, Mac, and Linux, so you don't have to pay for new hardware to write apps.
• SDK built into Java. If you are familiar with the Java programming language, you are already halfway there.
• Given the distribution of the application through the Android Market, it will be immediately available to hundreds of thousands of users. You are not limited to the official Market, as there are alternatives. For example, you can publish the app on your blogs. Amazon is rumored to be preparing its own Android app store.
• As well as the SDK technical documentation, new resources are being created for Android developers. The platform is gaining more and more popularity among users and developers.

Enough talk - let's start Android app development!

Installing Eclipse and Android SDK

Orientation for the Android platform during development

Before you start writing Android applications, you need to download the SDK for the Android platform. Each platform has its own version of the Android SDK installed on users' devices. For Android 1.5 and above, there are two platforms: Android Open Source Project and Google.

Android Open Source Project - an open source platform source code but does not include Google extensions, such as Google Maps. If you don't want to use the Google API, the functionality google maps will not be available for your application. Unless you have a specific reason to do this, I would recommend that you target one of the Google platforms, as this will allow you to use Google's own extensions.

• Select Window->Android SDK and AVD Manager.
• Click Available Packages in the left column and check the repository to show a list of available Android platforms.
• You can select platforms to download from the list, or leave all checked to download all available platforms. When finished, click Install Selected and follow the installation instructions.

Once everything has been successfully uploaded, you are ready to start Android development.

Create a new Android project

The Eclipse New Project Wizard will help you create an Android application by generating files and code ready to run on the right side of the block. This fast way make sure it works and a good starting point when starting to develop applications:

After clicking Finish, Eclipse will create a new Android project ready to be run and developed for Android. Remember when you told Eclipse to spawn an Activity called BrewClockActivity? This is the code that Android actually uses to run the app. The generated code will be displayed as a simple 'Hello World' message.

Packages

The package name is an identifier for your application. When it's time to publish the result to the Android Market, this ID will be used to track updates for the app, so it's important to make sure this ID is unique. Although we are using the name com.example.brewclock here, for a real application it is better to choose something like com.yourcompanyname.yourapplication.

SDK versions

Min SDK Version (name speaks for itself) - the earliest android version on which the application will run. With every new release of Android, the SDK adds and changes various methods. When you select an SDK version, Android (and the Android Market) knows that your app will only run on devices running the Android platform version of the specified version and higher.

Launching your application

Now let's try to run our application in Eclipse. Since this is the first run, Eclipse will ask you which project type you are working with:

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

Eclipse will try to run the application on the Android device. On this moment, however, you do not have devices under Android control, so the project will fail to run and you will be prompted to create a new Android Virtual Device (AVD).

Virtual devices (Android Virtual Devices)

Android Virtual Device (AVD) emulates the Android environment, be it mobile phone or tablet PC. You can create as many AVD devices as you like, with different versions of the Android platform. For each AVD, you can configure various device settings such as physical keyboard, GP support, camera resolution, and so on.

Before running the application, you must create your first AVD device with the platform SDK (Google API, 1.6).

Let's do it now:

• If you haven't tried running the application yet, press Run (or the keyboard shortcut Ctrl+F11)
• When the warning pops up, click Yes to create the AVD.
• Click New in the Android SDK and AVD Manager dialog.
• Set the following parameters for AVD: Name: Android_1.6 Target: Google APIs (Google Inc.) - API Level 4 SD Card Size: 16 MiB Skin Built In: Default (HVGA)
• Click Create AVD.
• Close the Android SDK and AVD Manager dialog.

Running code

Try running the application again (Ctrl + F11). Eclipse will now create your project and launch the new AVD. Remember, AVD completely emulates the Android environment, and you don't even have to watch the slow boot process as you would with a real device. For this reason, once the AVD is ready to go, it's best not to close the window until you've finished programming, throughout the day.

Android Development: User Interface Design

One of the first steps to creating any program at all is designing the user interface. Here is a small sketch of our application:

The user will be able to set the boil time in minutes using the + and - buttons. When he presses Start, the countdown will begin for the specified number of minutes. If the user cancels the boil by pressing the button again, the time will be extended when the timer reaches 0.

Interface building

The Android user interface, or skin, which is described in the XML documentation, can be found in the res/layouts folder. The template code, already generated by Eclipse, is declared in res/layouts/main.xml and, as you can see, is already running in the emulator.

Eclipse has its own layout design tool that allows you to create an interface by dragging and dropping within the screen. However, it is sometimes easier to write the interface in XML and use a graphical layout to preview the results.

Let's do it now by modifying main.xml to match the sketch above:

• Open res/layouts/main.xml in Eclipse double tap from Package Explorer.
• Select the main.xml tab at the bottom of the screen to switch to XML mode.

Now let's change the content of main.xml to the following:

# /res/layouts/main.xml

As you can see, there are a lot of files in Android XML, but this will allow you to control almost every element on the screen.

One of the most important UI elements in Android are Layout containers such as the LinearLayout used in this example. These elements are invisible to the user but act as containers for other elements such as Buttons and TextViews.

There are several layout layout types, each of which is used to build various types layouts. Like LinearLayout and AbsoluteLayout, TableLayout allows for a grid-based interface. You can learn more about this in the General Layout of Objects section of the API documentation.

Linking Your Layout to Code

After saving the layout, try running the application in the emulator by pressing Ctrl + F11, or by clicking the Run icon in Eclipse. Now, instead of the "Hello World" message, you will see that Android now displays the application's interface.

If you press any button, they will light up as expected, but don't do anything beyond that. Let's continue coding after the layout interface:

# /src/com/example/brewclock/BrewClockActivity.java ... import android.widget.Button; import android.widget.TextView; public class BrewClockActivity extends Activity ( /** Properties **/ protected Button brewAddTime; protected Button brewDecreaseTime; protected Button startBrew; protected TextView brewCountLabel; protected TextView brewTimeLabel; ... )

Next, we'll change the call to onCreate. This call occurs whenever an application is launched on Android. In the code generated by Eclipse, onCreate creates an activity view on R.layout.main. This is the line of code that instructs Android to decode the layout of the XML document and display it to the user.

Resource Object

In Android, R is special object, which is automatically generated to provide access to your project resources (layouts, strings, menus, icons...) inside the code. Each resource is assigned its own id. In the layout file (see above) these are the @+id XML attributes. We'll use these to bind Buttons and TextViews in our layout:

# /src/com/example/brewclock/BrewClockActivity.java ... public class BrewClockActivity extends Activity ( ... public void onCreate(Bundle savedInstanceState) ( super.onCreate(savedInstanceState); setContentView(R.layout.main); / / Connect interface elements to properties brewAddTime = (Button) findViewById(R.id.brew_time_up); brewDecreaseTime = (Button) findViewById(R.id.brew_time_down); startBrew = (Button) findViewById(R.id.brew_start); brewCountLabel = (TextView) findViewById(R.id.brew_count_label); brewTimeLabel = (TextView) findViewById(R.id.brew_time); ) )

Listening to events

To detect button presses, we need to implement a listener for them. You may be familiar with callback listeners, or callbacks, from other frameworks such as Javascript/JQuery or Rails.

Android provides a similar mechanism by providing a Listener interface, such as OnClickListener , that define methods that will fire when the event occurs. The OnClickListener interface will notify your application when the user clicks on the screen or a specific button. In addition, you need to tell each button about the ClickListener:

# /src/com/example/brewclock/BrewClockActivity.java ... // Be sure not to import // `android.content.dialoginterface.OnClickListener`. import android.view.View.OnClickListener; public class BrewClockActivity extends Activity implements OnClickListener ( ... public void onCreate(Bundle savedInstanceState) ( ... // Setup ClickListeners brewAddTime.setOnClickListener(this); brewDecreaseTime.setOnClickListener(this); startBrew.setOnClickListener(this); ) .. .public void onClick(View v) ( // TODO: Add code to handle button taps ) )

Next, we'll add the code that handles each of our button presses. We will also add four new Activity properties that will allow the user to set and track the brew time: how many brews have been made and whether the timer has been started.

# /src/com/example/brewclock/BrewClockActivity.java ... public class BrewClockActivity extends Activity implements OnClickListener ( ... protected int brewTime = 3; protected CountDownTimer brewCountDownTimer; protected int brewCount = 0; protected boolean isBrewing = false; . .. public void onClick(View v) ( if(v == brewAddTime) setBrewTime(brewTime + 1); else if(v == brewDecreaseTime) setBrewTime(brewTime -1); else if(v == startBrew) ( if( isBrewing) stopBrew(); else startBrew(); ) ) )

Note that we are using the CountDownTimer class provided by Android. This makes it easy to create and run a simple counter and receive notifications at regular intervals while the countdown is running. You will use this in the startBrew method, read about it below.

The following methods are models for the behavior of the slider for setting the brew time, start and stop brew, and the counter. We also initialize the brewTime and brewCount properties in onCreate.

It would be good practice to move this code to a separate model class, but for simplicity we will add the code to BrewClockActivity:

# /src/com/example/brewclock/BrewClockActivity.java ... public class BrewClockActivity extends Activity implements OnClickListener ( ... public void onCreate(Bundle savedInstanceState) ( ... // Set the initial brew values ​​setBrewCount(0); setBrewTime(3); ) /** * Set an absolute value for the number of minutes to brew. * Has no effect if a brew is currently running. * @param minutes The number of minutes to brew. */ public void setBrewTime( int minutes) ( if(isBrewing) return; brewTime = minutes; if(brewTime< 1) brewTime = 1; brewTimeLabel.setText(String.valueOf(brewTime) + "m"); } /** * Set the number of brews that have been made, and update * the interface. * @param count The new number of brews */ public void setBrewCount(int count) { brewCount = count; brewCountLabel.setText(String.valueOf(brewCount)); } /** * Start the brew timer */ public void startBrew() { // Create a new CountDownTimer to track the brew time brewCountDownTimer = new CountDownTimer(brewTime * 60 * 1000, 1000) { @Override public void onTick(long millisUntilFinished) { brewTimeLabel.setText(String.valueOf(millisUntilFinished / 1000) + "s"); } @Override public void onFinish() { isBrewing = false; setBrewCount(brewCount + 1); brewTimeLabel.setText("Brew Up!"); startBrew.setText("Start"); } }; brewCountDownTimer.start(); startBrew.setText("Stop"); isBrewing = true; } /** * Stop the brew timer */ public void stopBrew() { if(brewCountDownTimer != null) brewCountDownTimer.cancel(); isBrewing = false; startBrew.setText("Start"); } ... }

Only the Android-specific parts of this code create label displays using the setText method. In startBrew we create and run a CountDownTimer to start counting down per second when the brew/boil is over. Note that we are defining CountDownTimer listeners (onTick and onFinish). onTick will be called every 1000 milliseconds (1 second), while onFinish is called when the timer reaches zero.

Avoiding Complexity in Android Programming

To keep this guide for development under android simple, I deliberately used labels directly in the code (for example, "Brew Up!", "Start", "Stop"). Actually, it's not very good practice, as it makes it difficult to find and change these lines in large projects.

Android provides a neat way to keep your text strings separate from the R object code. R allows you to define all application strings in an XML file (res/values/strings.xml) that can be accessed in your code by reference. For example:

# /res/values/strings.xml Brew up!... # /res/com/example/brewclock/BrewClockActivity.java ... brewLabel.setText(R.string.brew_up_label); ...

Now if you want to change Brew Up! something else, you need to change it once in the strings.xml file. If your app contains dozens of code files, having labels in one place makes a lot of sense!

Checking BrewClock

We've finished writing the code, and it's time to "test" the application. Press "Run" or Ctrl + F11 to run BrewClock in the emulator. If everything went well, you will see the setup interface and are ready to brew tea! Try setting different brew times and press Start to count down.

Summary

In this brief introduction to Android development, you downloaded and installed the Android SDK and the Eclipse Android Development Tools (ADT) plugin. You have set up an emulator or virtual device to test your applications. You have also created a working android application which highlighted a number of key concepts , which you will use when developing future Android applications.

Hopefully this will whet your appetite for creating mobile apps and experimenting in this exciting area. Android offers a great way to write apps for a range of current and future mobile devices. If you have already written a working application for this platform, don't forget to let us know in the comments!

The Android SDK offers a custom plugin for the Eclipse IDE called Android Development Tools (ADT). This plugin provides a powerful framework in which to develop Android applications. This extends the capabilities of Eclipse, allowing you to quickly create new android projects, create the application interface, debug the application, export signatures for application packages (APKs) and distribute them.

Note: You must install the ADT plugin if you already have Eclipse installed and want to continue using it. If Eclipse has not been installed, you must install the complete android package An SDK that includes the latest IDE for Android developers.

Your existing installation Eclipse for Android must meet the following requirements:

• Eclipse 3.7.2 (Indigo) or higher

  Note: Eclipse 3.6 (Helios) is no longer supported with the latest version of ADT.

• Eclipse JDT plugin (included in most Eclipse IDE packages)
• JDK 6 (JRE is not enough)
• Not compatible with GNU Compiler for Java (GCJ)

Download ADT Plugin

To add ADT plugin to Eclipse for Android:

1. Launch Eclipse, then select Help > Install New Software (Help > install new software).
2. Click Add in the top right corner.
3. In the Add Repository dialog, in the dialog that appears, enter "ADT Plugin" for the Name ( Name) and the next address for Location(location):https: //dl-ssl.google.com/android/eclipse/

   Note: Android Developer Tools requires a secure connection when updating. Make sure the update URL you enter starts with HTTPS.

4. Click OK.
5. In the Available Software dialog box, check the box next to Developer Tools and click Further.
6. Further.
7. Read and accept the terms of the license agreement, and then click Ready.

   If you receive a security warning that the authenticity and validity software cannot be installed, click anyway OK.

8. After installation is complete, restart Eclipse.

Configuring the ADT Plugin

After Eclipse for Android is restarted, you need to specify the location of your Android SDK directory:

1. In the "Welcome" window that appears, select Use existing SDKs (Use existing SDKs).
2. Specify the location of the Android SDK directory where you recently downloaded and extracted the files.
3. Click Further.

Your Eclipse IDE is built for development android applications, but you must add the new Platform SDKs and Android Framework for your environment. To get these packages for your SDK, continue Adding Platforms and Packages.

Troubleshooting Installing ADT

If you're having trouble loading the ADT plugin after following the steps above and you're working with a firewall (such as a corporate firewall), make sure you've properly configured your proxy settings in Eclipse for Android. In Eclipse, you can configure the proxy from the Eclipse main menu, under Window(on Mac OS X, Eclipse)> Preferences> General > Network Connections.

If you are still unable to use Eclipse, you can download the ADT archive from local computer and install it manually:

1. Download ADT Plugin zip archive (do not unpack it):

   Plastic bag	Size	Amount MD5
   ADT-23.0.2.zip	103287135 bytes

2. Start Eclipse then select Help > Install New Software (Help > Install new software).
3. Click Add in the upper right corner.
4. In the add repository dialog, click Archive.
5. Select the downloaded ADT-23.0.2.zip file and click OK.
6. Enter "ADT Plugin" as the name and click OK.
7. In the Available Software dialog box, check the box next to Developer Tools and click Further.
8. In the next window, you will see a list of tools that will be loaded. Click Next.
9. Read and accept the terms of the license agreement, and then click Ready.

   If you receive a security warning that the authenticity and validity of the software cannot be established, click anyway. OK .

10. Once the installation is complete, restart Eclipse for Android.

Other installation errors

Please note that ADT has its own peculiarities. For example, some optional packages for Eclipse (eg WST) are required. If you encounter an error installing ADT, your Eclipse may not include these packages. For information on how to quickly add the necessary packages to your Eclipse installation, see the topic troubleshooting.

For Linux Users

If this error occurred while installing the ADT Plugin for Eclipse:

An error occurred during provisioning. Cannot connect to keystore . JKS

This means your system does not have a suitable Java VM. Installing Sun Java 6 will resolve this issue and you can then reinstall the ADT Plugin.

Problem

You want to use the Eclipse environment to develop your application for the Android platform.

Solution

Install the Eclipse environment and the AndMore plugin. Then create your project and start writing the application. Build it and test it with an emulator in the Eclipse environment.

Discussion

Before you can start building an application using the Eclipse environment, you need to install three items:

• Eclipse IDE
• Android SDK
• AndMore module

For details on installing these items, see .

After you do this, create a new Android project using the menu File → New (File → New), and you will see a screen like in fig. 1.

Select the SDK version for the target device (Figure 3). Version 4.0 covers almost every device in use today; later versions provide even more options. You decide!

Rice. 1.

Rice. 2.

Rice. 3.

On fig. Figure 4 shows the project structure expanded in the project pane on the right. It also shows to what extent you can use Eclipse autocomplete on the android platform - I added a gravity attribute to the label and the Eclipse environment suggests full list possible attribute values. I chose central-horizontal , so the label should be centered when the app starts.

Rice. 4.

If you set the gravity attribute in the LinearLayout to center_vertical and in the TextView to center_horizontal , then the text will be centered both vertically and horizontally. Listing 1 shows the corresponding main.xml layout file (located in the res/layout directory).

Listing 1. File hello world. java

As always, when you save a source file, Eclipse generates a compiled version. In the Android project, it also creates a compiled APK that's ready to run, so you only need to run it. Right-click on the project and select the command Run As → Android Application (Run as → Application for the Android platform) (Fig. 5).

This article will describe how to set up Eclipse for Android application development. I will list all the necessary software: 1) JDK 6 (Java Development Kit - Java Development Kit) 2) Eclipse Classic 3) Android SDK (Software Development Kit - Software Development Kit) 4) ADT (Android Development Tools - Tools for Android development ) - plugin for Eclipse JDK The JDK installation process is described in the article: Eclipse After installing the JDK, let's move on to installing Eclipse. Download the latest version of Eclipse from the official site eclipse.org. Click on bookmark Downloads, you will be presented with various builds of Eclipse. For our purposes, we need classic Eclipse - Eclipse Classic(at the time of writing latest version was 4.2.2). Unpack the downloaded archive into a directory c:\eclipse(or wherever you prefer) For convenience, create a shortcut to executable file eclipse.exe. Run eclipse. On first launch, you will be prompted to select a directory for your workspace. Workspaces group projects. If one workspace is enough for you, then you can set the flag "Use this as the default and don't ask again". By setting this flag, eclipse will not display this window next time, and will immediately open your default workspace. Android SDK Go to the download page http://d.android.com/sdk On this page, it is proposed to say an assembly that has everything you need for android development. But we will go the other way. Download only Android SDK. Select an item "DOWNLOAD FOR OTHER PLATFORMS"(download for other platforms), in the table titled "SDK Tools Only"(SDK only) download the Windows SDK installer (*.exe). After reading and agreeing to the license agreement, download this installer. Before Android installation SDK needs to be configured environment variable JAVA_HOME(), otherwise the installer will swear without finding the JDK. Run the installer installer_r21.1-windows.exe. In the welcome window, click Next
In the next step, the installer determines the location JDK by system variable JAVA_HOME. If the JDK is found, click the button "next".
In the user selection window, select the option "Install for anyone this computer"(install for all computer users). If you want to install only for yourself, then select the second option "Install just for me". Click "next".
In the window for choosing the installation location, leave everything as default and click "next".
In the window for creating a shortcut in the menu, you can also leave everything unchanged and click .
After successful installation, click "next".
In the final window of the installer, leave a checkmark "Start SDK Manager", to start it SDK Manager, after pressing the button "Finish".
Once launched, the SDK Manager will prompt you to install the latest version of the API. If you need previous versions, specify them and click the button "Install packages..."
Agree with the license "Accept License" and press
The download of your selected packages from the Internet will begin. ADT Installing the ADT plugin for Eclipse. We start Eclipse. On the menu Help select "Install New Software...". Click the button "Add..."(Add) Add storage window will appear:
Give it a name Android Development Tools and location address "https://dl-ssl.google.com/android/eclipse/". Click "OK" After a few seconds of waiting, an entry should appear in the list "Development Tools", tick it and click "next". In the next window, also click "next". In the license agreement overview, agree to it and click "Finish". A window will pop up during installation. Security Warning just click in it OK. Upon completion of the plugin installation ADT will be prompted to restart Eclipse, agree to this. At startup Eclipse the following error may occur:
Eclipse can't find the SDK because we installed the default SDK in the directory: C:\Program Files (x86)\Android\android-sdk. To reassign the path to the SDK, open the menu Windows -> Preferences. In the window Preferences in field SDK Location indicate the path to Android SDK and press OK.
All Eclipse ready for development Android-applications.

Android provides a special plugin for the Eclipse IDE called Android Development Tools (ADT). It provides a powerful IDE in which you can build Android applications. ADT extends the power of Eclipse so that you can quickly and easily create a new Android project, design user interface applications, debug the application, and export APK files to distribute your application.

Comment: If you prefer to work in a different IDE, then you don't need to install either Eclispe or ADT. Instead, you can directly use the SDK's capabilities to build and debug your application.

Download ADT plugin

1. Start Eclipse, select Help > Install New Software.
2. Click Add in the upper right corner.
3. In the Add Repository dialog that appears, enter "ADT Plugin" in the field Name and the following url in the field location:

https://dl-ssl.google.com/android/eclipse/

1. Click OK.

If you have problems when trying to get the plugin, then try in the field location write "http" instead of "https" (https is used for security reasons).

1. In the Available Software dialog, check the box next to Developer Tools and click Next.
2. In the next window, you will see a list of tools to download. Click Next.
3. Read and accept the license agreement, then click Finish.

If you receive security warnings that the authenticity and validity of the software cannot be established, click OK.

1. After installation is complete, restart Eclipse.

Configuring the ADT Plugin

After restarting Eclipse, you must specify the directory with your Android SDK:

1. Select Use existing SDKs in the window that appears.
2. Find and select the directory containing the Android SDK that you recently downloaded and unpacked.
3. Click Next.

Troubleshoot installation

If you are having difficulty downloading the ADT plugin after the steps above, then here are some solutions:

• If Eclipse cannot find the remote update site containing the ADT plugin, then try changing the site link to

http://dl-ssl.google.com/android/eclipse/

• If you have a firewall (or corporate firewall) enabled, make sure you have entered the correct proxy settings in Eclipse. In Eclipse, you can set up proxy from the main menu from Window(on Mac OS X, Eclipse)> Preferences > General > Network Connections.

If you are still unable to download the ADT plugin using Eclipse from the remote update site, you can download the ADT zip file to your computer and install it manually:

For Linux Users

If you are facing problem installing ADT plugin for Eclipse view:

An error occurred during provisioning. Cannot connect to keystore. JKS

This means that you do not have a suitable Java VM on your computer. Installing Sun Java 6 will solve this problem and then you can reinstall the ADT plugin.