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Reference link: e rror:Failed to resolve: com.android. support:appcompat-v7 :29

Cause: Android studio updates the SDK version to the latest version

Error: failed to resolve: com.android.com support:appcompat-v7 :29

Analysis: the version of Android SDK tools under sdkmanager is 26.1.1

Solution: modify the build. Gradle file in the app directory

　　1.compileSdkVersion 29 -> compileSdkVersion 26

　　2.targetSdkVersion 26 -> targetSdkVersion 26

　　3.com.android. support:appcompat-v7 :29.+ -> com.android. support:appcompat-v7 :26.+