Build-tools corresponds to buildToolsVersion in gradle configuration
Generally, we have several versions in the folder, the purpose is to facilitate the compilation of old projects and third-party projects online. If you do not have the required version in your folder, the compilation will fail. There are two solutions: one is to download the required version. The second is to change the buildToolsVersion version number, but in that case, the corresponding V4 and V7 compatible packages will also need to be changed.
The docs folder
I’ve never been able to open it
Extras folder
Some USB driver files (), v4 and V7 packages are put here?
Platforms corresponds to targetSdkVersion in the Gradle configuration
Store different SDK versions
platform-tools
Exe, sqlite3.exe, which contains platform-dependent development and debugging tools for developing apps
Samples folder
Sources folder
Save android source code, AS with its own decompilation function, can decompilate.class files, but if the source code down, you can directly find the.java file, which has a large number of comments (learn android source code good place)
The system – the images folder
The space for storing virtual machines takes up a lot of space
Tools folder
DDMS tools, including testing, debugging, third party tools. Simulators, data management tools, etc.
add-ons
Download some third-party frameworks to make this framework appear
aidl
Convert the. Aidl interface to a Java interface.
Ensure that the SDK Build Tools version, Gradle version and Gradle Plugin version are compatible with Android Studio.
Focus on the Gradle version because the Gradle version determines the SDK Build Tools version and Gradle Plugin version.
Refer to the reference
https://www.jianshu.com/p/23f7d8b1cb0b