Some problems with the first Android studio project

At first, I was using Android studio3.1 to get the ". Gradle" problem. The workaround is https://www.zhihu.com/question/37810416. Add Build.gradle in Project

Maven {URL ' http://maven.aliyun.com/nexus/content/groups/public/'}
maven{url ' http://maven.aliyun.com/nexus/content/repositories/jcenter '}

When configuring the HTTP proxy, I used the Dalian Neusoft Information Institute mirror server address:
-http://mirrors.neusoft.edu.cn Port: 80

I changed to Android studio2.3 because I had a problem next. First, I met

Gradle Sync Failed:could Not the Find Method Android () for arguments [[email protected]] on root project ' Firstapplication ' O F Type Org.gradle.api.Project.
Consult IDE Log for + details (Help | Show Log)

The workaround is to remove the Build.gradle in project

android{

}

dependencies{

}

The reason is that the build.gradle in the app already has these two things. Reference: Issues in StackOverflow.

Second encounter: Failed to resolve:junit:junit:4.12, there is a similar.

The workaround is: https://stackoverflow.com/questions/36992657/failed-to-resolve-junitjunit12.

I don't understand the specific reason.

The compilation is complete.

Some problems with the first Android studio project