title: error when i want to compile gradle zxing
body: <p>im trying to use zxing to scan barcode using android studio 
  but when i try to add zxing gradle i got this error </p>
  
  <pre><code>Error:Execution failed for task ':app:transformClassesWithJarMergingForAristiDebug'.
  &gt; com.android.build.api.transform.TransformException: java.util.zip.ZipException: duplicate entry: com/google/zxing/BarcodeFormat.class
  </code></pre>
  
  <p>this is what all gradle i have </p>
  
  <pre><code>compile 'com.android.support:appcompat-v7:25.3.1'
      compile 'com.android.support:design:25.3.1'
      compile 'com.android.support:cardview-v7:25.3.1'
      compile 'com.android.support:recyclerview-v7:25.3.1'
      compile 'com.jakewharton:butterknife:8.4.0'
      compile 'com.jakewharton:butterknife-compiler:8.4.0'
      compile 'com.squareup.retrofit2:retrofit:2.1.0'
      compile 'com.squareup.okhttp3:logging-interceptor:3.4.1'
      compile 'com.squareup.okhttp3:okhttp:3.4.1'
      compile 'com.squareup.retrofit2:converter-gson:2.1.0'
      compile 'com.squareup.retrofit2:adapter-rxjava:2.1.0'
      compile 'com.github.bumptech.glide:glide:3.7.0'
      compile 'de.hdodenhof:circleimageview:2.1.0'
      compile 'org.greenrobot:eventbus:3.0.0'
      compile 'com.google.android.gms:play-services-maps:10.2.1'
      compile 'com.google.android.gms:play-services-location:10.2.1'
      compile 'com.karumi:dexter:2.3.1'
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
      compile 'me.dm7.barcodescanner:zxing:1.9'    
      testCompile 'junit:junit:4.12'
  </code></pre>
  
  <p>can somebody tell me what should i do ?? Or what should i search to remove this error ?</p>