1 page.title=Developing In Eclipse, with ADT 2 @jd:body 3 4 <div id="qv-wrapper"> 5 <div id="qv"> 6 <h2>In this document</h2> 7 <ol> 8 <li><a href="#CreatingAProject">Creating an Android Project</a></li> 9 <li><a href="#AVD">Creating an AVD</a></li> 10 <li><a href="#Running">Running Your Application</a> 11 <ol> 12 <li><a href="#RunningOnEmulator">Running on the emulator</a></li> 13 <li><a href="#RunningOnDevice">Running on a device</a></li> 14 </ol> 15 </li> 16 <li><a href="#RunConfig">Creating a Custom Run Configuration</a></li> 17 <li><a href="#Signing">Setting Up Application Signing</a></li> 18 <li><a href="#libraryProject">Working with Library Projects</a> 19 <ol> 20 <li><a href="#libraryReqts">Development requirements</a></li> 21 <li><a href="#librarySetup">Setting up a library project</a></li> 22 <li><a href="#libraryReference">Referencing a library project</a></li> 23 <li><a href="#considerations">Development considerations</a></li> 24 <li><a href="#libraryMigrating">Migrating library projects to ADT 0.9.8</a></li> 25 </ol> 26 </li> 27 <li><a href="#Tips">Eclipse Tips</a></li> 28 </div> 29 </div> 30 31 32 <p>The Android Development Tools (ADT) plugin for Eclipse adds powerful extensions to the Eclipse 33 integrated development environment. It allows you to create and debug Android applications easier 34 and faster. If you use Eclipse, the ADT plugin gives you an incredible boost in developing Android 35 applications:</p> 36 37 <ul> 38 <li>It gives you access to other Android development tools from inside the Eclipse IDE. For 39 example, ADT lets you access the many capabilities of the DDMS tool: take screenshots, manage 40 port-forwarding, set breakpoints, and view thread and process information directly from 41 Eclipse.</li> 42 <li>It provides a New Project Wizard, which helps you quickly create and set up all of the 43 basic files you'll need for a new Android application.</li> 44 <li>It automates and simplifies the process of building your Android application.</li> 45 <li>It provides an Android code editor that helps you write valid XML for your Android 46 manifest and resource files.</li> 47 <li>It will even export your project into a signed APK, which can be distributed to users.</li> 48 </ul> 49 50 <p>To begin developing Android applications in the Eclipse IDE with ADT, you first need to 51 download the Eclipse IDE and then download and install the ADT plugin. To do so, follow the 52 steps given in <a href="{@docRoot}sdk/eclipse-adt.html#installing">Installing 53 the ADT Plugin</a>.</p> 54 55 <p>If you are already developing applications using a version of ADT earlier than 0.9, make 56 sure to upgrade to the latest version before continuing. See the guide to 57 <a href="{@docRoot}sdk/eclipse-adt.html#updating">Updating Your ADT Plugin</a>.</p> 58 59 <p class="note"><strong>Note:</strong> This guide assumes you are using the latest version of 60 the ADT plugin. While most of the information covered also applies to previous 61 versions, if you are using an older version, you may want to consult this document from 62 the set of documentation included in your SDK package (instead of the online version).</p> 63 64 65 <h2 id="CreatingAProject">Creating an Android Project</h2> 66 67 <p>The ADT plugin provides a New Project Wizard that you can use to quickly create a new 68 Android project (or a project from existing code). To create a new project:</p> 69 70 <ol> 71 <li>Select <strong>File</strong> > <strong>New</strong> > <strong>Project</strong>.</li> 72 <li>Select <strong>Android</strong> > <strong>Android Project</strong>, and click 73 <strong>Next</strong>.</li> 74 <li>Select the contents for the project: 75 <ul> 76 <li>Enter a <em>Project Name</em>. This will be the name of the folder where your 77 project is created.</li> 78 <li>Under Contents, select <strong>Create new project in workspace</strong>. 79 Select your project workspace location.</li> 80 <li>Under Target, select an Android target to be used as the project's Build Target. 81 The Build Target 82 specifies which Android platform you'd like your application built against. 83 <p>Unless you know that you'll be using new APIs introduced in the latest SDK, you should 84 select a target with the lowest platform version possible.</p> 85 <p class="note"><strong>Note:</strong> You can change your the Build Target for your 86 project at any time: Right-click the project in the Package Explorer, select 87 <strong>Properties</strong>, select <strong>Android</strong> and then check 88 the desired Project Target.</p> 89 </li> 90 <li>Under Properties, fill in all necessary fields. 91 <ul> 92 <li>Enter an <em>Application name</em>. This is the human-readable title for your 93 application — the name that will appear on the Android device.</li> 94 <li>Enter a <em>Package name</em>. This is the package namespace (following the same rules 95 as for packages in the Java programming language) where all your source code 96 will reside.</li> 97 <li>Select <em>Create Activity</em> (optional, of course, but common) and enter a name 98 for your main Activity class.</li> 99 <li>Enter a <em>Min SDK Version</em>. This is an integer that indicates 100 the minimum API Level required to properly run your application. 101 Entering this here automatically sets the <code>minSdkVersion</code> attribute in the 102 <a href="{@docRoot}guide/topics/manifest/uses-sdk-element.html"><uses-sdk></a> 103 of your Android Manifest file. If you're unsure of the appropriate <a 104 href="{@docRoot}guide/appendix/api-levels.html">API Level</a> to use, 105 copy the API Level listed for the Build Target you selected in the Target tab.</li> 106 </ul> 107 </li> 108 </ul> 109 </li> 110 <li>Click <strong>Finish</strong>.</li> 111 </ol> 112 113 <p class="note"><strong>Tip:</strong> 114 You can also start the New Project Wizard from the <em>New</em> icon in the toolbar.</p> 115 116 <p>Once you complete the New Project Wizard, ADT creates the following 117 folders and files in your new project:</p> 118 <dl> 119 <dt><code>src/</code></dt> 120 <dd>Includes your stub Activity Java file. All other Java files for your application 121 go here.</dd> 122 <dt><code><em><Android Version></em>/</code> (e.g., <code>Android 1.1/</code>)</dt> 123 <dd>Includes the <code>android.jar</code> file that your application will build against. 124 This is determined by the build target that you have chosen in the <em>New Project 125 Wizard</em>.</dd> 126 <dt><code>gen/</code></dt> 127 <dd>This contains the Java files generated by ADT, such as your <code>R.java</code> file 128 and interfaces created from AIDL files.</dd> 129 <dt><code>assets/</code></dt> 130 <dd>This is empty. You can use it to store raw asset files. </dd> 131 <dt><code>res/</code></dt> 132 <dd>A folder for your application resources, such as drawable files, layout files, string 133 values, etc. See 134 <a href="{@docRoot}guide/topics/resources/index.html">Application Resources</a>.</dd> 135 <dt><code>AndroidManifest.xml</code></dt> 136 <dd>The Android Manifest for your project. See 137 <a href="{@docRoot}guide/topics/manifest/manifest-intro.html">The AndroidManifest.xml 138 File</a>.</dd> 139 <dt><code>default.properties</code></dt> 140 <dd>This file contains project settings, such as the build target. This files is integral 141 to the project, as such, it should be maintained in a Source Revision Control system. 142 It should never be edited manually — to edit project properties, 143 right-click the project folder and select "Properties".</dd> 144 </dl> 145 146 147 <h2 id="AVD">Creating an AVD</h2> 148 149 <p>An Android Virtual Device (AVD) is a device configuration for the emulator that 150 allows you to model real world devices. In order to run an instance of the emulator, you must create 151 an AVD.</p> 152 153 <p>To create an AVD from Eclipse:</p> 154 155 <ol> 156 <li>Select <strong>Window > Android SDK and AVD Manager</strong>, or click the Android SDK and 157 AVD Manager icon in the Eclipse toolbar.</p> 158 </li> 159 <li>In the <em>Virtual Devices</em> panel, you'll see a list of existing AVDs. Click 160 <strong>New</strong> to create a new AVD.</li> 161 <li>Fill in the details for the AVD. 162 <p>Give it a name, a platform target, an SD card size, and 163 a skin (HVGA is default).</p> 164 <p class="note"><strong>Note:</strong> Be sure to define 165 a target for your AVD that satisfies your application's Build Target (the AVD 166 platform target must have an API Level equal to or greater than the API Level that your 167 application compiles against).</p> 168 </li> 169 <li>Click <strong>Create AVD</strong>.</li> 170 </ol> 171 172 <p>Your AVD is now ready and you can either close the SDK and AVD Manager, create more AVDs, or 173 launch an emulator with the AVD by selecting a device and clicking <strong>Start</strong>.</p> 174 175 <p>For more information about AVDs, read the 176 <a href="{@docRoot}guide/developing/tools/avd.html">Android Virtual Devices</a> 177 documentation.</p> 178 179 180 <h2 id="Running">Running Your Application</h2> 181 182 <div class="sidebox-wrapper"> 183 <div class="sidebox"> 184 <h2>Use the Emulator to Test Different Configurations</h2> 185 <p>Create multiple AVDs that each define a different device configuration with which your 186 application is compatible, then launch each AVD into a new emulator from the SDK and AVD Manager. 187 Set the target mode in your app's run configuration to manual, so that when you run your 188 application, you can select from the available virtual devices.</p> 189 </div> 190 </div> 191 192 <p>Running your application from Eclipse will usually require just a couple clicks, whether you're 193 running it on the emulator or on an attached device. The information below describes how to get 194 set up and run your application from Eclipse.</p> 195 196 <h3 id="RunningOnEmulator">Running on the emulator</h3> 197 198 <p>Before you can run your application on the Android Emulator, 199 you <strong>must</strong> <a href="#AVD">create an AVD</a>.</p> 200 201 <p>To run (or debug) your application, select <strong>Run</strong> > <strong>Run</strong> (or 202 <strong>Run</strong> > <strong>Debug</strong>) from the Eclipse menu bar. The ADT plugin 203 will automatically create a default launch configuration for the project. Eclipse will then perform 204 the following:</p> 205 206 <ol> 207 <li>Compile the project (if there have been changes since the last build).</li> 208 <li>Create a default launch configuration (if one does not already exist for the 209 project).</li> 210 <li>Install and start the application on an emulator (or device), based on the Deployment 211 Target 212 defined by the run configuration. 213 <p>By default, Android run configurations use an "automatic target" mode for 214 selecting a device target. For information on how automatic target mode selects a 215 deployment target, see <a href="#AutoAndManualTargetModes">Automatic and manual 216 target modes</a> below.</p> 217 </li> 218 </ol> 219 220 <p>If debugging, the application will start in the "Waiting For Debugger" mode. Once the 221 debugger is attached, Eclipse will open the Debug perspective.</p> 222 223 <p>To set or change the launch configuration used for your project, use the launch configuration 224 manager. 225 See <a href="#launchconfig">Creating a Launch Configuration</a> for information.</p> 226 227 <p>Be certain to create multiple AVDs upon which to test your application. You should have one AVD 228 for each platform and screen type with which your application is compatible. For 229 instance, if your application compiles against the Android 1.5 (API Level 3) platform, you should 230 create an AVD for each platform equal to and greater than 1.5 and an AVD for each <a 231 href="{@docRoot}guide/practices/screens_support.html">screen type</a> you support, then test 232 your application on each one.</p> 233 234 235 <h3 id="RunningOnDevice">Running on a device</h3> 236 237 <p>Before you can run your application on a device, you must perform some basic setup for your 238 device:</p> 239 240 <ul> 241 <li>Declare your application as debuggable in your manifest</li> 242 <li>Enable USB Debugging on your device</li> 243 <li>Ensure that your development computer can detect your device when connected via USB</li> 244 </ul> 245 <p>Read <a href="{@docRoot}guide/developing/device.html#setting-up">Setting up a Device for 246 Development</a> for more information.</p> 247 248 <p>Once set up and your device is connected via USB, install your application on the device by 249 selecting <strong>Run</strong> > <strong>Run</strong> (or 250 <strong>Run</strong> > <strong>Debug</strong>) from the Eclipse menu bar.</p> 251 252 253 254 <h2 id="RunConfig">Creating a Run Configuration</h2> 255 256 <p>The run configuration specifies the project to run, the Activity 257 to start, the emulator or connected device to use, and so on. When you first run a project 258 as an <em>Android Application</em>, ADT will automatically create a run configuration. 259 The default run configuration will 260 launch the default project Activity and use automatic target mode for device selection 261 (with no preferred AVD). If the default settings don't suit your project, you can 262 customize the launch configuration or even create a new.</p> 263 264 <p>To create or modify a launch configuration, follow these steps as appropriate 265 for your Eclipse version:</p> 266 267 <ol> 268 <li>Open the run configuration manager. 269 <ul> 270 <li>In Eclipse 3.3 (Europa), select <strong>Run</strong> > 271 <strong>Open Run Dialog</strong> (or <strong>Open Debug Dialog</strong>) 272 </li> 273 <li>In Eclipse 3.4 (Ganymede), select <strong>Run </strong>> 274 <strong>Run Configurations</strong> (or 275 <strong>Debug Configurations</strong>) 276 </li> 277 </ul> 278 </li> 279 <li>Expand the <strong>Android Application</strong> item and create a new 280 configuration or open an existing one. 281 <ul> 282 <li>To create a new configuration: 283 <ol> 284 <li>Select <strong>Android Application</strong> and click the <em>New launch 285 configuration</em> 286 icon above the list (or, right-click <strong>Android Application</strong> and click 287 <strong>New</strong>).</li> 288 <li>Enter a Name for your configuration.</li> 289 <li>In the Android tab, browse and select the project you'd like to run with the 290 configuration.</li> 291 </ol> 292 <li>To open an existing configuration, select the configuration name from the list 293 nested below <strong>Android Application</strong>.</li> 294 </ul> 295 </li> 296 <li>Adjust your desired launch configuration settings. 297 <p>In the Target tab, consider whether you'd like to use Manual or Automatic mode 298 when selecting an AVD to run your application. 299 See the following section on <a href=#AutoAndManualModes">Automatic and manual target 300 modes</a>).</p> 301 <p>You can specify any emulator options to the Additional Emulator Command 302 Line Options field. For example, you could add <code>-scale 96dpi</code> to 303 scale the AVD's screen to an accurate size, based on the dpi of your 304 computer monitor. For a full list of emulator options, see the <a 305 href="{@docRoot}guide/developing/tools/emulator.html">Android Emulator</a> 306 document.</p> 307 </li> 308 </ol> 309 310 311 <h3 id="AutoAndManualTargetModes">Automatic and manual target modes</h3> 312 313 <p>By default, a run configuration uses the <strong>automatic</strong> target mode in order to 314 select an AVD. In this mode, ADT will select an AVD for the application in the following manner:</p> 315 316 <ol> 317 <li>If there's a device or emulator already running and its AVD configuration 318 meets the requirements of the application's build target, the application is installed 319 and run upon it.</li> 320 <li>If there's more than one device or emulator running, each of which meets the requirements 321 of the build target, a "device chooser" is shown to let you select which device to use.</li> 322 <li>If there are no devices or emulators running that meet the requirements of the build target, 323 ADT looks at the available AVDs. If one meets the requirements of the build target, 324 the AVD is used to launch a new emulator, upon which the application is installed and run.</li> 325 <li>If all else fails, the application will not be run and you will see a console error warning 326 you that there is no existing AVD that meets the build target requirements.</li> 327 </ol> 328 329 <p>However, if a "preferred AVD" is selected in the run configuration, then the application 330 will <em>always</em> be deployed to that AVD. If it's not already running, then a new emulator 331 will be launched.</p> 332 333 <p>If your run configuration uses <strong>manual</strong> mode, then the "device chooser" 334 is presented every time that your application is run, so that you can select which AVD to use.</p> 335 336 337 <h2 id="Signing">Signing your Applications</h2> 338 339 <p>As you begin developing Android applications, understand that all 340 Android applications must be digitally signed before the system will install 341 them on an emulator or an actual device. There are two ways to do this: 342 with a debug key (for immediate testing on an emulator or development device) 343 or with a private key (for application distribution).</p> 344 345 <p>The ADT plugin helps you get started quickly by signing your .apk files with 346 a debug key, prior to installing them on an emulator or development device. This means that you can 347 quickly run your application from Eclipse without having to 348 generate your own private key. No specific action on your part is needed, 349 provided ADT has access to Keytool.However, please note that if you intend 350 to publish your application, you <strong>must</strong> sign the application with your 351 own private key, rather than the debug key generated by the SDK tools.</p> 352 353 <p>Please read <a href="{@docRoot}guide/publishing/app-signing.html">Signing Your 354 Applications</a>, which provides a thorough guide to application signing on Android 355 and what it means to you as an Android application developer. The document also includes 356 a guide to exporting and signing your application with the ADT's Export Wizard.</p> 357 358 359 <h2 id="libraryProject">Working with Library Projects</h2> 360 361 <div class="sidebox-wrapper"> 362 <div class="sidebox"> 363 <h2>Library project example code</h2> 364 365 <p>The SDK includes an example application called TicTacToeMain that shows how a 366 dependent application can use code and resources from an Android Library 367 project. The TicTacToeMain application uses code and resources from an example 368 library project called TicTacToeLib. 369 370 <p style="margin-top:1em;">To download the sample applications and run them as 371 projects in your environment, use the <em>Android SDK and AVD Manager</em> to 372 download the "Samples for SDK API 8" component into your SDK. </p> 373 374 <p style="margin-top:1em;">For more information and to browse the code of the 375 samples, see the <a 376 href="{@docRoot}resources/samples/TicTacToeMain/index.html">TicTacToeMain 377 application</a>.</p> 378 </div> 379 </div> 380 381 <p>An Android <em>library project</em> is a development project that holds 382 shared Android source code and resources. Other Android application projects can 383 reference the library project and, at build time, include its compiled sources 384 in their <code>.apk</code> files. Multiple application projects can reference 385 the same library project and any single application project can reference 386 multiple library projects. </p> 387 388 <p>If you have source code and resources that are common to multiple application 389 projects, you can move them to a library project so that it is easier to 390 maintain across applications and versions. Here are some common scenarios in 391 which you could make use of library projects: </p> 392 393 <ul> 394 <li>If you are developing multiple related applications that use some of the 395 same components, you could move the redundant components out of their respective 396 application projects and create a single, reuseable set of the same components 397 in a library project. </li> 398 <li>If you are creating an application that exists in both free and paid 399 versions, you could move the part of the application that is common to both versions 400 into a library project. The two dependent projects, with their different package 401 names, will reference the library project and provide only the difference 402 between the two application versions.</li> 403 </ul> 404 405 <p>Structurally, a library project is similar to a standard Android application 406 project. For example, it includes a manifest file at the project root, as well 407 as <code>src/</code>, <code>res/</code> and similar directories. The project can 408 contain the same types of source code and resources as a standard 409 Android project, stored in the same way. For example, source code in the library 410 project can access its own resources through its <code>R</code> class. </p> 411 412 <p>However, a library project differs from an standard Android application 413 project in that you cannot compile it directly to its own <code>.apk</code> or 414 run it on the Android platform. Similarly, you cannot export the library project 415 to a self-contained JAR file, as you would do for a true library. Instead, you 416 must compile the library indirectly, by referencing the library from a dependent 417 application's build path, then building that application. </p> 418 419 <p>When you build an application that depends on a library project, the SDK 420 tools compile the library and merge its sources with those in the main project, 421 then use the result to generate the <code>.apk</code>. In cases where a resource 422 ID is defined in both the application and the library, the tools ensure that the 423 resource declared in the application gets priority and that the resource in the 424 library project is not compiled into the application <code>.apk</code>. This 425 gives your application the flexibility to either use or redefine any resource 426 behaviors or values that are defined in any library.</p> 427 428 <p>To organize your code further, your application can add references to 429 multiple library projects, then specify the relative priority of the resources 430 in each library. This lets you build up the resources actually used in your 431 application in a cumulative manner. When two libraries referenced from an 432 application define the same resource ID, the tools select the resource from the 433 library with higher priority and discard the other. </p> 434 435 <p>ADT lets you add references to library projects and set their relative 436 priority from the application project's Properties. As shown in Figure 2, 437 below, once you've added a reference to a library project, you can use the 438 <strong>Up</strong> and <strong>Down</strong> controls to change the ordering, 439 with the library listed at the top getting the higher priority. At build time, 440 the libraries are merged with the application one at a time, starting from the 441 lowest priority to the highest. </p> 442 443 <p>Note that a library project cannot itself reference another library project 444 and that, at build time, library projects are <em>not</em> merged with each 445 other before being merged with the application. However, note that a library can 446 import an external library (JAR) in the normal way.</p> 447 448 <p>The sections below describe how to use ADT to set up and manage library your 449 projects. Once you've set up your library projects and moved code into them, you 450 can import library classes and resources to your application in the normal way. 451 </p> 452 453 454 <h3 id="libraryReqts">Development requirements</h3> 455 456 <p>Android library projects are a build-time construct, so you can use them to 457 build a final application <code>.apk</code> that targets any API level and is 458 compiled against any version of the Android library. </p> 459 460 <p>However, to use library projects, you need to update your development 461 environment to use the latest tools and platforms, since older releases of the 462 tools and platforms do not support building with library projects. Specifically, 463 you need to download and install the versions listed below:</p> 464 465 <p class="table-caption"><strong>Table 1.</strong> Minimum versions of SDK tools 466 and plaforms on which you can develop library projects.</p> 467 468 <table> 469 <tr> 470 <th>Component</th> 471 <th>Minimum Version</th> 472 </tr> 473 <tr> 474 <td>SDK Tools</td> 475 <td>r6 (or higher)</td> 476 </tr> 477 <tr><td>Android 2.2 platform</td><td>r1 (or higher)</td></tr> 478 <tr><td>Android 2.1 platform</td><td>r2 (or higher)</td></tr> 479 <tr><td style="color:gray">Android 2.0.1 platform</td><td style="color:gray"><em>not supported</em></td></tr> 480 <tr><td style="color:gray">Android 2.0 platform</td><td style="color:gray"><em>not supported</em></td></tr> 481 <tr><td>Android 1.6 platform</td><td>r3 (or higher)</td></tr> 482 <tr><td>Android 1.5 platform</td><td>r4 (or higher)</td></tr> 483 <tr><td>ADT Plugin</td><td>0.9.7 (or higher)</td></tr> 484 </table> 485 486 <p>You can download the tools and platforms using the <em>Android SDK and AVD 487 Manager</em>, as described in <a href="{@docRoot}sdk/adding-components.html">Adding SDK 488 Components</a>. To install or update ADT, use the Eclipse Updater as described 489 in <a href="{@docRoot}sdk/eclipse-adt.html">ADT Plugin for Eclipse</a>.</p> 490 491 492 <h3 id="librarySetup">Setting up a library project</h3> 493 494 <p>A library project is a standard Android project, so you can create a new one in the 495 same way as you would a new application project. Specifically, you can use 496 the New Project Wizard, as described in <a href="#CreatingAProject">Creating an 497 Android Project</a>, above. </p> 498 499 <p>When you are creating the library project, you can select any application 500 name, package, and set other fields as needed, as shown in the diagram below. 501 Click Finish to create the project in the workspace.</p> 502 503 <p>Next, set the project's Properties to indicate that it is a library project:</p> 504 505 <ol> 506 <li>In the <strong>Package Explorer</strong>, right-click the library project 507 and select <strong>Properties</strong>.</li> 508 <li>In the <strong>Properties</strong> window, select the "Android" properties 509 group at left and locate the <strong>Library</strong> properties at right. </li> 510 <li>Select the "is Library" checkbox and click <strong>Apply</strong>.</li> 511 <li>Click <strong>OK</strong> to close the <strong>Properties</strong> window.</li> 512 </ol> 513 514 <p>The new project is now marked as a library project. You can begin moving 515 source code and resources into it, as described in the sections below. </p> 516 517 <p>You can also convert an existing application project into a library. To do 518 so, simply open the Properties for the project and select the "is Library" 519 checkbox. Other application projects can now reference the existing project as a 520 library project.</p> 521 522 <img src="{@docRoot}images/developing/adt-props-isLib.png" style="margin:0;padding:0;" /> 523 <p class="img-caption" style="margin-left:3em;margin-bottom:2em;"><strong>Figure 1.</strong> 524 Marking a project as an Android library project. </p> 525 526 <h4>Creating the manifest file</h4> 527 528 <p>A library project's manifest file must declare all of the shared components 529 that it includes, just as would a standard Android application. For more 530 information, see the documentation for <a 531 href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a>.</p> 532 533 <p>For example, the <a 534 href="{@docRoot}resources/samples/TicTacToeLib/AndroidManifest.html">TicTacToeLib</a> 535 example library project declares the Activity <code>GameActivity</code>: </p> 536 537 <pre><manifest> 538 ... 539 <application> 540 ... 541 <activity android:name="GameActivity" /> 542 ... 543 </application> 544 ... 545 </manifest></pre> 546 547 548 <h3 id="libraryReference">Referencing a library project from an application</h3> 549 550 <p>If you are developing an application and want to include the shared code or 551 resources from a library project, you can do so easily by adding a reference to 552 the library project in the application project's Properties.</p> 553 554 <p>To add a reference to a library project, follow these steps: </p> 555 556 <ol> 557 <li>In the <strong>Package Explorer</strong>, right-click the dependent project 558 and select <strong>Properties</strong>.</li> 559 <li>In the <strong>Properties</strong> window, select the "Android" properties group 560 at left and locate the <strong>Library</strong> properties at right.</li> 561 <li>Click <strong>Add</strong> to open the <strong>Project Selection</strong> 562 dialog. </li> 563 <li>From the list of available library projects, select a project and click 564 <strong>OK</strong>.</li> 565 <li>When the dialog closes, click <strong>Apply</strong> in the 566 <strong>Properties</strong> window.</li> 567 <li>Click <strong>OK</strong> to close the <strong>Properties</strong> window.</li> 568 </ol> 569 570 <p>As soon as the Properties dialog closes, Eclipse rebuilds the project, 571 including the contents of the library project. </p> 572 573 <p>The figure below shows the Properties dialog that lets you add library 574 references and move them up and down in priority. </p> 575 576 <img src="{@docRoot}images/developing/adt-props-libRef.png" style="margin:0;padding:0;" /> 577 <p class="img-caption" style="margin-left:3em;margin-bottom:2em;"><strong>Figure 2.</strong> 578 Adding a reference to a library project in the properties of an application project. </p> 579 580 <p>If you are adding references to multiple libraries, note that you can set 581 their relative priority (and merge order) by selecting a library and using the 582 <strong>Up</strong> and <strong>Down</strong> controls. The tools merge the 583 referenced libraries with your application starting from lowest priority (bottom 584 of the list) to highest (top of the list). If more than one library defines the 585 same resource ID, the tools select the resource from the library with higher 586 priority. The application itself has highest priority and its resources are 587 always used in preference to identical resource IDs defined in libraries.</p> 588 589 <h4>Declaring library components in the the manifest file</h4> 590 591 <p>In the manifest file of the application project, you must add declarations 592 of all components that the application will use that are imported from a library 593 project. For example, you must declare any <code><activity></code>, 594 <code><service></code>, <code><receiver></code>, 595 <code><provider></code>, and so on, as well as 596 <code><permission></code>, <code><uses-library></code>, and similar 597 elements.</p> 598 599 <p>Declarations should reference the library components by their fully-qualified 600 package names, where appropriate. </p> 601 602 <p>For example, the <a 603 href="{@docRoot}resources/samples/TicTacToeMain/AndroidManifest.html">TicTacToeMain</a> 604 example application declares the library Activity <code>GameActivity</code> 605 like this: </p> 606 607 <pre><manifest> 608 ... 609 <application> 610 ... 611 <activity android:name="com.example.android.tictactoe.library.GameActivity" /> 612 ... 613 </application> 614 ... 615 </manifest></pre> 616 617 <p>For more information about the manifest file, see the documentation for <a 618 href="{@docRoot}guide/topics/manifest/manifest-intro.html">AndroidManifest.xml</a>.</p> 619 620 621 <h3 id="considerations">Development considerations</h3> 622 623 <p>As you develop your library project and dependent applications, keep the 624 points listed below in mind.</p> 625 626 <p><strong>Resource conflicts</strong></p> 627 628 <p>Since the tools merge the resources of a library project with those of a 629 dependent application project, a given resource ID might be defined in both 630 projects. In this case, the tools select the resource from the application, or 631 the library with highest priority, and discard the other resource. As you 632 develop your applications, be aware that common resource IDs are likely to be 633 defined in more than one project and will be merged, with the resource from the 634 application or highest-priority library taking precedence.</p> 635 636 <p><strong>Using prefixes to avoid resource conflicts</strong></p> 637 638 <p>To avoid resource conflicts for common resource IDs, consider using a prefix 639 or other consistent naming scheme that is unique to the project (or is unique 640 across all projects). </p> 641 642 <p><strong>No export of library project to JAR</strong></p> 643 644 <p>A library cannot be distributed as a binary file (such as a jar file). This 645 is because the library project is compiled by the main project to use the 646 correct resource IDs.</p> 647 648 <p><strong>A library project can include a JAR library</strong></p> 649 650 <p>You can develop a library project that itself includes a JAR library, however 651 you need to manually edit the dependent application project's build path and add 652 a path to the JAR file. </p> 653 654 <p><strong>A library project can depend on an external JAR library</strong></p> 655 656 <p>You can develop a library project that depends on an external library (for 657 example, the Maps external library). In this case, the dependent application 658 must build against a target that includes the external library (for example, the 659 Google APIs Add-On). Note also that both the library project and the dependent 660 application must declare the external library their manifest files, in a <a 661 href="{@docRoot}guide/topics/manifest/uses-library-element.html"><code><uses-library></code></a> 662 element. </p> 663 664 <p><strong>Library project can not include raw assets</strong></p> 665 666 <p>The tools do not support the use of raw asset files in a library project. 667 Any asset resources used by an application must be stored in the 668 <code>assets/</code> directory of the application project 669 itself.</p> 670 671 <p><strong>Targeting different Android platform versions in library project and 672 application project</strong></p> 673 674 <p>A library is compiled as part of the dependent application project, so the 675 API used in the library project must be compatible with the version of the 676 Android library used to compile the application project. In general, the library 677 project should use an <a href="{@docRoot}guide/appendix/api-levels.html">API level</a> 678 that is the same as — or lower than — that used by the application. 679 If the library project uses an API level that is higher than that of the 680 application, the application project will fail to compile. It is perfectly 681 acceptable to have a library that uses the Android 1.5 API (API level 3) and 682 that is used in an Android 1.6 (API level 4) or Android 2.1 (API level 7) 683 project, for instance.</p> 684 685 <p><strong>No restriction on library package name</strong></p> 686 687 <p>There is no requirement for the package name of a library to be the same as 688 that of applications that use it.</p> 689 690 <p><strong>Multiple R classes in gen/ folder of application project</strong></p> 691 692 <p>When you build the dependent application project, the code of any libraries 693 is compiled and merged to the application project. Each library has its own 694 <code>R</code> class, named according to the library's package name. The 695 <code>R</code> class generated from the resources of the main project and of the 696 library is created in all the packages that are needed including the main 697 projects package and the libraries packages.</p> 698 699 <p><strong>Testing a library project</strong></p> 700 701 <p>There are two recommended ways of setting up testing on code and resources in 702 a library project: </p> 703 704 <ul> 705 <li>You can set up a <a 706 href="{@docRoot}guide/developing/testing/testing_otheride.html">test project</a> 707 that instruments an application project that depends on the library project. You 708 can then add tests to the project for library-specific features.</li> 709 <li>You can set up a set up a standard application project that depends on the 710 library and put the instrumentation in that project. This lets you create a 711 self-contained project that contains both the tests/instrumentations and the 712 code to test.</li> 713 </ul> 714 715 <p><strong>Library project storage location</strong></p> 716 717 <p>There are no specific requirements on where you should store a library 718 project, relative to a dependent application project, as long as the application 719 project can reference the library project by a relative link. You can place the 720 library project What is important is that the main project can reference the 721 library project through a relative link.</p> 722 723 <h3 id="libraryMigrating">Migrating library projects to ADT 0.9.8</h3> 724 725 <p>This section provides information about how to migrate a library project 726 created with ADT 0.9.7 to ADT 0.9.8 (or higher). The migration is needed only if 727 you are developing in Eclipse with ADT and assumes that you have also upgraded 728 to SDK Tools r7 (or higher). </p> 729 730 <p>The way that ADT handles library projects has changed between 731 ADT 0.9.7 and ADT 0.9.8. Specifically, in ADT 0.9.7, the <code>src/</code> 732 source folder of the library was linked into the dependent application project 733 as a folder that had the same name as the library project. This worked because 734 of two restrictions on the library projects:</p> 735 736 <ul> 737 <li>The library was only able to contain a single source folder (excluding the 738 special <code>gen/</code> source folder), and</li> 739 <li>The source folder was required to have the name <code>src/</code> and be 740 stored at the root of the project.</li> 741 </ul> 742 743 <p>In ADT 0.9.8, both of those restrictions were removed. A library project can 744 have as many source folders as needed and each can have any name. Additionally, 745 a library project can store source folders in any location of the project. For 746 example, you could store sources in a <code>src/java/</code> directory. In order 747 to support this, the name of the linked source folders in the main project are 748 now called <<em>library-name</em>>_<<em>folder-name</em>> For 749 example: <code>MyLibrary_src/</code> or <code>MyLibrary_src_java/</code>.</p> 750 751 <p>Additionally, the linking process now flags those folders in order for ADT to 752 recognize that it created them. This will allow ADT to automatically migrate the 753 project to new versions of ADT, should they contain changes to the handling of 754 library projects. ADT 0.9.7 did not flag the linked source folders, so ADT 0.9.8 755 cannot be sure whether the old linked folders can be removed safely. After 756 upgrading ADT to 0.9.8, you will need to remove the old linked folders manually 757 in a simple two-step process, as described below.</p> 758 759 <p>Before you begin, make sure to create a backup copy of your application or 760 save the latest version to your code version control system. This ensures that 761 you will be able to easily revert the migration changes in case there is a 762 problem in your environment.</p> 763 764 <p>When you first upgrade to ADT 0.9.8, your main project will look as shown 765 below, with two linked folders (in this example, <code>MyLibrary</code> and 766 <code>MyLibrary_src</code> — both of which link to 767 <code>MyLibrary/src</code>. Eclipse shows an error on one of them because they 768 are duplicate links to a single class.</p> 769 770 <img src="{@docRoot}images/developing/lib-migration-0.png" alt=""> 771 772 <p>To fix the error, remove the linked folder that <em>does not</em> contain the 773 <code>_src</code> suffix. </p> 774 775 <ol> 776 <li>Right click the folder that you want to remove (in this case, the 777 <code>MyLibrary</code> folder) and choose <strong>Build Path</strong> > 778 <strong>Remove from Build Path</strong>, as shown below.</li> 779 780 <img src="{@docRoot}images/developing/lib-migration-1.png" style="height:600px" 781 alt=""> 782 783 <li>Next, When asked about unlinking the folder from the project, select 784 <strong>Yes</strong>, as shown below.</li> 785 786 <img src="{@docRoot}images/developing/lib-migration-2.png" alt=""> 787 </ol> 788 789 <p>This should resolve the error and migrate your library project to the new 790 ADT environment. </p> 791 792 <h2 id="Tips">Eclipse Tips</h2> 793 794 <h3 id="arbitraryexpressions">Executing arbitrary Java expressions in Eclipse</h3> 795 796 <p>You can execute arbitrary code when paused at a breakpoint in Eclipse. For example, 797 when in a function with a String argument called "zip", you can get 798 information about packages and call class methods. You can also invoke arbitrary 799 static methods: for example, entering <code>android.os.Debug.startMethodTracing()</code> will 800 start dmTrace. </p> 801 <p>Open a code execution window, select <strong>Window</strong> > <strong>Show 802 View</strong> > <strong>Display</strong> from the main menu to open the 803 Display window, a simple text editor. Type your expression, highlight the 804 text, and click the 'J' icon (or CTRL + SHIFT + D) to run your 805 code. The code runs in the context of the selected thread, which must be 806 stopped at a breakpoint or single-step point. (If you suspend the thread 807 manually, you have to single-step once; this doesn't work if the thread is 808 in Object.wait().)</p> 809 <p>If you are currently paused on a breakpoint, you can simply highlight and execute 810 a piece of source code by pressing CTRL + SHIFT + D. </p> 811 <p>You can highlight a block of text within the same scope by pressing ALT +SHIFT 812 + UP ARROW to select larger and larger enclosing blocks, or DOWN ARROW to select 813 smaller blocks. </p> 814 <p>Here are a few sample inputs and responses in Eclipse using the Display window.</p> 815 816 <table width="100%" border="1"> 817 <tr> 818 <th scope="col">Input</th> 819 <th scope="col">Response</th> 820 </tr> 821 <tr> 822 <td><code>zip</code></td> 823 <td><code>(java.lang.String) 824 /work/device/out/linux-x86-debug/android/app/android_sdk.zip</code></td> 825 </tr> 826 <tr> 827 <td><code>zip.endsWith(".zip")</code></td> 828 <td><code>(boolean) true</code></td> 829 </tr> 830 <tr> 831 <td><code>zip.endsWith(".jar")</code></td> 832 <td><code>(boolean) false</code></td> 833 </tr> 834 </table> 835 <p>You can also execute arbitrary code when not debugging by using a scrapbook page. 836 Search the Eclipse documentation for "scrapbook".</p> 837 838 839 <h3>Running DDMS Manually</h3> 840 841 <p>Although the recommended way to debug is to use the ADT plugin, you can manually run 842 DDMS and configure Eclipse to debug on port 8700. (<strong>Note: </strong>Be sure that you 843 have first started <a href="{@docRoot}guide/developing/tools/ddms.html">DDMS</a>). </p> 844 845 846 847 848 <!-- TODO: clean this up and expand it to cover more wizards and features 849 <h3>ADT Wizards</h3> 850 851 <p>Notice that the "New Android Project" wizard has been expanded to use the multi-platform 852 capabilities of the new SDK.</p> 853 854 <p>There is now a "New XML File" wizard that lets you create skeleton XML resource 855 files for your Android projects. This makes it easier to create a new layout, a new menu, a 856 new strings file, etc.</p> 857 858 <p>Both wizards are available via <strong>File > New</strong> and new icons in the main 859 Eclipse toolbar (located to the left of the Debug and Run icons). 860 If you do not see the new icons, you may need to select <strong>Window > Reset 861 Perspective</strong> from the Java perspective.</p> 862 --> 863