Flutter编译问题app:transformDexArchi

FAILURE: Build failed with an exception.

* What went wrong:

Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.

> java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex

* Try:

Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 2s

Finished with error: Gradle task assembleDebug failed with exit code 1

项目原来都是好好的，可以正常运行，后面打开运行突然就报这个错误。也没找到clean的地方。别着急，查了一下Flutter命令。

解决方案，在Android Studio的Terminal中输入命令：flutter clean

再次运行就OK啦！