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.
解决方法:
方法一:点击build-->clean Project
方法二:(原因:由于.build中的compileSdkVersion,产生所依赖的dependency与当前版本不一致导致错误)
点击build-->Rebuild Project
方法三:项目中将build.gradle文件中依赖的包,都根据AS提示将版本改成最新的之后, 将project的build.gradle中的gradle版本修改