Is there a buildToolsVersion option?

Question

After upgrading to Android studio 3.0 and creating a new project, I noticed that it was buildToolsVersionmissing and the project was working fine.

therefore, it is clearly optional. my question is:
is this always the case or is this a new change?

how the version is selected, if I did not specify it. my first thought is that it is automatically installed on the latest version installed in the SDK manager, but I found that it is installed build_tools_version: \"26.1.0\"in android-studio\build\android-profile\profile-2017-10-30-16-28-12-121.json
despite the build_tools: version 27.0.0installed in my SDK manager.
it only changed 27.0.0after adding manually buildToolsVersion '27.0.0'inbuild.gradle

What is the best practice of adding buildToolsVersionin build.gradlesince it is now in the default template in AS 3.0 and 3.1?

Answer 1

If you noted the release notes for the SDK assembly tools , it says:

By default, the Android SDK uses the latest downloaded version of Build Tools. If your projects depend on older versions of Build Tools, the SDK Manager allows you to download and maintain separate versions of tools for use with these projects.

So yes, it is optional and is the last one by default.