用android studio打包apk出现错误提示

Question

在android studio里用真机或虚拟机测试都没有问题，app都能够正常运行。但是用android studio打包apk时却出现错误提示
1.Error:Error converting bytecode to dex:
Cause: com.android.dex.DexException: Multiple dex files define Landroid/support/v7/app/ActionBar$DisplayOptions;
2.Error:Execution failed for task ':app:transformClassesWithDexForRelease'.

com.android.build.api.transform.TransformException: com.android.ide.common.process.ProcessException: java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException

Answer 1

dex 文件重复定义了 Landroid/support/v7/app/ActionBar$DisplayOptions;