在app下的build.gradle文件中的dependences {}中添加如下代码：
androidTestCompile(‘com.android.support:support-annotations:26.1.0‘) { force = true }
添加后dependences中结构类似
dependencies { androidTestCompile(‘com.android.support:support-annotations:26.1.0‘) { force = true } ... }
Error:Execution failed for task ':app:preDebugAndroidTestBuild'. > Conflict with dependency