Android AppCompat Library V7 » 28.0.0-alpha1 - Maven Repository
Android AppCompat Library V7. ». 28.0.0-alpha1. The Support Library is a static library that you can add to your Android application in order to use APIs that are either not available for older platform versions or utility APIs that aren't a part of the framework APIs. Compatible on devices running API 14 or later.
Android AppCompat Library V7 » 28.0.0-beta01 - Maven Repository
Try this: 1) tools -> android -> sdk manager -> Launch Standalone SDK Manager. 2) find "extras -> Android support repository" and check it (uncheck other for faster installing) 3) click install. Tip: Also use File -> Invalidate Caches / Restart if android studio does something strange. It may help in some cases.
Android studio com.android.support:appcompat-v7:+ problem
One of the common errors after installing Android Studio is the appcompat-v7 error. This error occurs due to the banning of Iran IPs and as a result of not receiving the file through Android Studio for users who launch their project from Iran.
How to install Repository com.android.support:appcompat-v7
Are you using AppCompat and setting an AppCompat theme? If so then it is needed. Note that the compiler will convert it to the relevant AndroidX class automatically.