title: Android Studio: Error:Execution failed for task ':app:dexDebug'
body: <p>I'm using Android Studio for the first time and I got the following error after importing the project (previously it was an eclipse project where I had issues too.)</p>
  
  <p>Here is the information given:</p>
  
  <pre><code>Error:Execution failed for task ':app:dexDebug'.
  &gt; com.android.ide.common.internal.LoggedErrorException: Failed to run command:
      /home/crash-id/Development/SDK/adt-bundle-linux-x86_64-20140702/sdk/build-tools/21.1.2/dx --dex --no-optimize --output /home/crash-id/AndroidstudioProjects/LocalSin/app/build/intermediates/dex/debug --input-list=/home/crash-id/AndroidstudioProjects/LocalSin/app/build/intermediates/tmp/dex/debug/inputList.txt
    Error Code:
      2
    Output:
      UNEXPECTED TOP-LEVEL EXCEPTION:
      com.android.dex.DexException: Multiple dex files define Lcom/google/ads/AdRequest$ErrorCode;
          at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)
          at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)
          at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)
          at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
          at com.android.dx.merge.DexMerger.merge(DexMerger.java:189)
          at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)
          at com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)
          at com.android.dx.command.dexer.Main.run(Main.java:246)
          at com.android.dx.command.dexer.Main.main(Main.java:215)
          at com.android.dx.command.Main.main(Main.java:106)
  
  :app:dexDebug
  UNEXPECTED TOP-LEVEL EXCEPTION:
  com.android.dex.DexException: Multiple dex files define Lcom/google/ads/AdRequest$ErrorCode;
      at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)
      at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)
      at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)
      at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
      at com.android.dx.merge.DexMerger.merge(DexMerger.java:189)
      at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)
      at com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)
      at com.android.dx.command.dexer.Main.run(Main.java:246)
      at com.android.dx.command.dexer.Main.main(Main.java:215)
      at com.android.dx.command.Main.main(Main.java:106)
  
  
   FAILED
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':app:dexDebug'.
  &gt; com.android.ide.common.internal.LoggedErrorException: Failed to run command:
      /home/crash-id/Development/SDK/adt-bundle-linux-x86_64-20140702/sdk/build-tools/21.1.2/dx --dex --no-optimize --output /home/crash-id/AndroidstudioProjects/LocalSin/app/build/intermediates/dex/debug --input-list=/home/crash-id/AndroidstudioProjects/LocalSin/app/build/intermediates/tmp/dex/debug/inputList.txt
    Error Code:
      2
    Output:
  
      UNEXPECTED TOP-LEVEL EXCEPTION:
      com.android.dex.DexException: Multiple dex files define Lcom/google/ads/AdRequest$ErrorCode;
          at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:596)
          at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:554)
          at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:535)
          at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
          at com.android.dx.merge.DexMerger.merge(DexMerger.java:189)
          at com.android.dx.command.dexer.Main.mergeLibraryDexBuffers(Main.java:454)
          at com.android.dx.command.dexer.Main.runMonoDex(Main.java:303)
          at com.android.dx.command.dexer.Main.run(Main.java:246)
          at com.android.dx.command.dexer.Main.main(Main.java:215)
          at com.android.dx.command.Main.main(Main.java:106)
  
  
  
  * Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
  
  BUILD FAILED
  </code></pre>
  
  <p>The app build.gradle is this:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 21
      buildToolsVersion "21.1.2"
  
      defaultConfig {
          applicationId "com.myapp.test"
          minSdkVersion 11
          targetSdkVersion 14
      }
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
          }
      }
  }
  
  dependencies {
      compile 'com.android.support:support-v4:18.0.0'
      compile 'com.android.support:appcompat-v7:21.0.3'
      compile 'com.google.android.gms:play-services:+'
      compile files('libs/google-play-services.jar')
      compile files('libs/httpcore-4.3.2.jar')
      compile files('libs/httpmime-4.3.4.jar')
  }
  </code></pre>
  
  <p>And the project built.gradle is this:</p>
  
  <pre><code>buildscript {
      repositories {
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:1.0.0'
      }
  }
  
  allprojects {
      repositories {
          jcenter()
      }
  }
  </code></pre>
  
  <p>Do you have any idea what the problem could be and how can it be solved? A good explanation for the problem would be useful too as I am new to Android Studio. Thanks in advance :)</p>