The

problem introduces

In the article on the Flutter development environment built on the Mac, when doctor is used to check whether other dependencies need to be installed, three problems are detected! , Doctor found issues in 3 categories.

[!] Android toolchain - develop for Android devices (Android SDK 27.0.3)
    ✗ Android license status unknown.

problem solved

from the error prompt, you need to add the Android license.
execute command:

flutter doctor --android-licenses

when prompted to accept the license, enter y to confirm, as follows:

Review licenses that have not been accepted (y/N)?y
All SDK package licenses accepted

if this command is executed, error is reported when:

A newer version of the Android SDK is required. To update, run:
/Users/***/Android/sdk/tools/bin/sdkmanager --update

you need to do

first

/Users/***/Android/sdk/tools/bin/sdkmanager --update

after this command is executed, execute doctor flutter --android-licenses.

validation

again doctor, you can see that the error on Android license is gone.