How to resolve this after successful build of app in android studio

问题

**Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.

com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex**

回答1:

Step1: Modify the module-level build.gradle file to enable multidex and add the multidex library as a dependency, as shown here:

android {
    defaultConfig {
        ...
        minSdkVersion 15 
        targetSdkVersion 26
        multiDexEnabled true
    }
    ...
}

dependencies {
  compile 'com.android.support:multidex:1.0.1'
}

Step 2: If you do override the Application class, change it to extend MultiDexApplication (if possible) as follows:

public class MyApplication extends MultiDexApplication { ... }

Or if you do override the Application class but it's not possible to change the base class, then you can instead override the attachBaseContext() method and call MultiDex.install(this) to enable multidex:

public class MyApplication extends SomeOtherApplication {
  @Override
  protected void attachBaseContext(Context base) {
     super.attachBaseContext(base);
     MultiDex.install(this);
  }
}

More info please check this link

回答2:

Add this in build.gradle file.

android {
      defaultConfig {
            multiDexEnabled true
      }
}

来源：https://stackoverflow.com/questions/46195895/how-to-resolve-this-after-successful-build-of-app-in-android-studio