具体问题：Error : Execution failed for task ’ :app: preDebugAndroidTestBuild’.Conflict with dependency ‘com.android.support:support-annotations’ in project ‘:app’. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.

解决方案：在app的build.gradle中的Android{...}添加如下代码：

configurations.all {
        resolutionStrategy.force ‘com.android.support:support-annotations:27.1.1‘
}

Android gradle报错