title: Android studio proguard error
body: <p>I enabled proguard to obfuscate the code of my application. Specifically, I would only obscure the activity of the application, but I get a lot of mistakes when creating the APK. This error also arises if imposed proguard true in libraries. Can anyone help me ?</p>
  
  <pre><code>    apply plugin: 'com.android.application'    
  
  android {         
      compileSdkVersion 23
      buildToolsVersion "23.0.2"
      defaultConfig {
          applicationId "my.packname"
          minSdkVersion 16
          targetSdkVersion 23
          versionCode 52
          versionName "2.0.2"
      }
      buildTypes {
          release {
              minifyEnabled true
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(include: ['*.jar'], dir: 'libs')
      compile files('libs/commons-codec-1.8.jar')
      compile files('libs/dropbox-android-sdk-1.6.3.jar')
      compile files('libs/httpmime-4.0.3.jar')
      compile files('libs/json_simple-1.1.jar')
      compile files('libs/pass-v1.2.1.jar')
      compile files('libs/sdk-v1.0.0.jar')    
      compile project(':library_edittext')
      compile project(':aFileChooser')
      compile project(':library_color_picker')
      compile project(':sqlcipher-for-android')
      compile project(':library_menu_main')
      compile 'io.reactivex:rxjava:1.0.10'    
      compile 'com.android.support:appcompat-v7:23.1.1'
      compile 'com.android.support:support-v4:23.1.1'
      compile 'com.android.support:design:23.1.1'
   }
  </code></pre>
  
  <p>error:</p>
  
  <pre><code> Warning:there were 87 unresolved references to classes or interfaces.
           You may need to add missing library jars or update their versions.
           If your code works fine without the missing classes, you can suppress
           the warnings with '-dontwarn' options.
           (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)
  Warning:Exception while processing task java.io.IOException: Please correct the above warnings first.
  :app:transformClassesAndResourcesWithProguardForRelease FAILED
  Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
  &gt; java.io.IOException: Please correct the above warnings first.
  
       Error:Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease'.
      &gt; java.io.IOException: Please correct the above warnings first.
  </code></pre>