title: react-native run-android failed with error: Execution failed for task ':app:dexDebug'
body: <p>I'm using windows 8.1. with 
  <code>react-native-cli: 1.0.0</code> and
  <code>react-native: 0.31.0</code> </p>
  
  <p>After adding <code>react-native-maps</code> to the project, I ran command <code>react-native upgrade</code> and given <strong>Y</strong> to all questions.
  Then linked deps with <code>rnpm link</code> as well as come changes to <code>MainApplication.java</code> file too.</p>
  
  <p>Here are changes to <code>MainApplication.java</code>:</p>
  
  <pre><code>// Other imports ...
  import com.airbnb.android.react.maps.MapsPackage;
  
  public class MainApplication extends Application implements ReactApplication {
  
   private final ReactNativeHost mReactNativeHost = new ReactNativeHost(this) {
      @Override
      protected boolean getUseDeveloperSupport() {
         return BuildConfig.DEBUG;
      }
  
      @Override
      protected List&lt;ReactPackage&gt; getPackages() {
        return Arrays.&lt;ReactPackage&gt;asList(
           new MainReactPackage(),
           new MapsPackage() // I have added this for react-native-maps
        );
      }
    };
  
   @Override
   public ReactNativeHost getReactNativeHost() {
     return mReactNativeHost;
   }
  }
  </code></pre>
  
  <p>Now I'm getting error when I run the command: <code>react-native run-android</code></p>
  
  <pre><code>λ react-native run-android                                                                    
  JS server already running.                                                                    
  Running C:\Program Files (x86)\Android\android-sdk/platform-tools/adb reverse tcp:8081 tcp:808
  1                                                                                             
  Building and installing the app on the device (cd android &amp;&amp; gradlew.bat installDebug...      
  :app:preBuild UP-TO-DATE                                                                      
  :app:preDebugBuild UP-TO-DATE                                                                 
  :app:checkDebugManifest                                                                       
  :app:preReleaseBuild UP-TO-DATE                                                               
  :react-native-maps:compileLint                                                                
  :react-native-maps:copyReleaseLint UP-TO-DATE                                                 
  :react-native-maps:preBuild UP-TO-DATE                                                        
  :react-native-maps:preReleaseBuild UP-TO-DATE                                                 
  :react-native-maps:checkReleaseManifest                                                       
  :react-native-maps:preDebugAndroidTestBuild UP-TO-DATE                                        
  :react-native-maps:preDebugBuild UP-TO-DATE                                                   
  :react-native-maps:preDebugUnitTestBuild UP-TO-DATE                                           
  :react-native-maps:preReleaseUnitTestBuild UP-TO-DATE                                         
  :react-native-maps:prepareComAndroidSupportAppcompatV72301Library UP-TO-DATE                  
  :react-native-maps:prepareComAndroidSupportRecyclerviewV72301Library UP-TO-DATE               
  :react-native-maps:prepareComAndroidSupportSupportV42321Library UP-TO-DATE                    
  :react-native-maps:prepareComFacebookFrescoDrawee0110Library UP-TO-DATE                       
  :react-native-maps:prepareComFacebookFrescoFbcore0110Library UP-TO-DATE                       
  :react-native-maps:prepareComFacebookFrescoFresco0110Library UP-TO-DATE                       
  :react-native-maps:prepareComFacebookFrescoImagepipeline0110Library UP-TO-DATE                
  :react-native-maps:prepareComFacebookFrescoImagepipelineBase0110Library UP-TO-DATE            
  :react-native-maps:prepareComFacebookFrescoImagepipelineOkhttp30110Library UP-TO-DATE         
  :react-native-maps:prepareComFacebookReactReactNative0310Library UP-TO-DATE                   
  :react-native-maps:prepareComFacebookSoloaderSoloader010Library UP-TO-DATE                    
  :react-native-maps:prepareComGoogleAndroidGmsPlayServicesBase840Library UP-TO-DATE            
  :react-native-maps:prepareComGoogleAndroidGmsPlayServicesBasement840Library UP-TO-DATE        
  :react-native-maps:prepareComGoogleAndroidGmsPlayServicesMaps840Library UP-TO-DATE            
  :react-native-maps:prepareOrgWebkitAndroidJscR174650Library UP-TO-DATE                        
  :react-native-maps:prepareReleaseDependencies                                                 
  :react-native-maps:compileReleaseAidl UP-TO-DATE                                              
  :react-native-maps:compileReleaseRenderscript UP-TO-DATE                                      
  :react-native-maps:generateReleaseBuildConfig UP-TO-DATE                                      
  :react-native-maps:generateReleaseAssets UP-TO-DATE                                           
  :react-native-maps:mergeReleaseAssets UP-TO-DATE                                              
  :react-native-maps:generateReleaseResValues UP-TO-DATE                                        
  :react-native-maps:generateReleaseResources UP-TO-DATE                                        
  :react-native-maps:mergeReleaseResources UP-TO-DATE                                           
  :react-native-maps:processReleaseManifest UP-TO-DATE                                          
  :react-native-maps:processReleaseResources UP-TO-DATE                                         
  :react-native-maps:generateReleaseSources UP-TO-DATE                                          
  :react-native-maps:processReleaseJavaRes UP-TO-DATE                                           
  :react-native-maps:compileReleaseJavaWithJavac UP-TO-DATE                                     
  :react-native-maps:extractReleaseAnnotations UP-TO-DATE                                       
  :react-native-maps:mergeReleaseProguardFiles UP-TO-DATE                                       
  :react-native-maps:packageReleaseJar UP-TO-DATE                                               
  :react-native-maps:compileReleaseNdk UP-TO-DATE                                               
  :react-native-maps:packageReleaseJniLibs UP-TO-DATE                                           
  :react-native-maps:packageReleaseLocalJar UP-TO-DATE                                          
  :react-native-maps:packageReleaseRenderscript UP-TO-DATE                                      
  :react-native-maps:packageReleaseResources UP-TO-DATE                                         
  :react-native-maps:bundleRelease UP-TO-DATE                                                   
  :app:prepareComAndroidSupportAppcompatV72301Library UP-TO-DATE                                
  :app:prepareComAndroidSupportRecyclerviewV72301Library UP-TO-DATE                             
  :app:prepareComAndroidSupportSupportV42321Library UP-TO-DATE                                  
  :app:prepareComFacebookFrescoDrawee0110Library UP-TO-DATE                                     
  :app:prepareComFacebookFrescoFbcore0110Library UP-TO-DATE                                     
  :app:prepareComFacebookFrescoFresco0110Library UP-TO-DATE                                     
  :app:prepareComFacebookFrescoImagepipeline0110Library UP-TO-DATE                              
  :app:prepareComFacebookFrescoImagepipelineBase0110Library UP-TO-DATE                          
  :app:prepareComFacebookFrescoImagepipelineOkhttp30110Library UP-TO-DATE                       
  :app:prepareComFacebookReactReactNative0310Library UP-TO-DATE                                 
  :app:prepareComFacebookSoloaderSoloader010Library UP-TO-DATE                                  
  :app:prepareComGoogleAndroidGmsPlayServicesBase840Library UP-TO-DATE                          
  :app:prepareComGoogleAndroidGmsPlayServicesBasement840Library UP-TO-DATE                      
  :app:prepareComGoogleAndroidGmsPlayServicesMaps840Library UP-TO-DATE                          
  :app:prepareNativeBaseDemoReactNativeMapsUnspecifiedLibrary UP-TO-DATE                        
  :app:prepareOrgWebkitAndroidJscR174650Library UP-TO-DATE                                      
  :app:prepareDebugDependencies                                                                 
  :app:compileDebugAidl UP-TO-DATE                                                              
  :app:compileDebugRenderscript UP-TO-DATE                                                      
  :app:generateDebugBuildConfig UP-TO-DATE                                                      
  :app:generateDebugAssets UP-TO-DATE                                                           
  :app:mergeDebugAssets UP-TO-DATE                                                              
  :app:generateDebugResValues UP-TO-DATE                                                        
  :app:generateDebugResources UP-TO-DATE                                                        
  :app:mergeDebugResources UP-TO-DATE                                                           
  :app:bundleDebugJsAndAssets SKIPPED                                                           
  :app:processDebugManifest UP-TO-DATE                                                          
  :app:processDebugResources UP-TO-DATE                                                         
  :app:generateDebugSources UP-TO-DATE                                                          
  :app:processDebugJavaRes UP-TO-DATE                                                           
  :app:compileDebugJavaWithJavac UP-TO-DATE                                                     
  :app:compileDebugNdk UP-TO-DATE                                                               
  :app:compileDebugSources UP-TO-DATE                                                           
  :app:preDexDebug UP-TO-DATE                                                                   
  :app:dexDebug                                                                                 
    Unknown source file : UNEXPECTED TOP-LEVEL EXCEPTION:                                         
    Unknown source file : com.android.dex.DexException: Multiple dex files define Landroid/support/v7/appcompat/R$anim;                                                                         
    Unknown source file :   at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)                                                                                             
    Unknown source file :   at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)  
    Unknown source file :   at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)  
    Unknown source file :   at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)      
    Unknown source file :   at com.android.dx.merge.DexMerger.merge(DexMerger.java:189)           
    Unknown source file :   at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:502)                                                                                          
    Unknown source file :   at com.android.dx.command.dexer.Main.runMonoDex(Main.java:334)        
    Unknown source file :   at com.android.dx.command.dexer.Main.run(Main.java:277)               
    Unknown source file :   at com.android.dx.command.dexer.Main.main(Main.java:245) 
  
    Unknown source file :   at com.android.dx.command.Main.main(Main.java:106)       
  :app:dexDebug FAILED                                                                          
  
  FAILURE: Build failed with an exception.                                                      
  
  * What went wrong:                                                                            
  Execution failed for task ':app:dexDebug'.                                                    
  &gt; com.android.ide.common.process.ProcessException: org.gradle.process.internal.ExecException: 
  Process 'command 'C:\Program Files\Java\jdk1.8.0_102\bin\java.exe'' finished with non-zero exit value 2                                                                                     
  
  * Try:                                                                                        
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.                                                                              
  
  BUILD FAILED                                                                                  
  
  Total time: 50.673 secs                                                                       
  Could not install the app on the device, read the error above for details.                    
  Make sure you have an Android emulator running or a device connected and have set up your Android development environment:                                                  
  https://facebook.github.io/react-native/docs/android-setup.html             
  </code></pre>
  
  <p>I have no idea about this error. Saw some questions similar to this but could not find the answer. I'm new to React-Native and Android development so I'm having hard time understanding this stuff.</p>