Android Multiple dex files define

Error:Execution failed for task ':app:transformClassesWithDexForDebug'.

> com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: com.android.dex.DexException: Multiple dex files define Landroid/support/v4/accessibilityservice/AccessibilityServiceInfoCompat$AccessibilityServiceInfoVersionImpl;

这个错误在app的build.gradle里面添加下面这句就好了。

android {

defaultConfig {

...

multiDexEnabled true

}

}