关于android studio 出现Error:Execution failed for task ‘:app:preDebugAndroidTestBuild‘. 的解决办法

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.

在app下的build.gradle文件中的dependences {}中添加如下代码：

dependencies {
  androidTestCompile('com.android.support:support-annotations:26.1.0') {
        force = true
    }
...
}