(The source code of the most popular 40 Android open source projects on GitHub has been selected. The main reason is to add what can be added to your projects. Here are descriptions of 40 projects, as well as the source code of 12 projects. All children's shoes in Sichuan Province have repeatedly downloaded. Of course, if there are children's shoes that need other projects, I also provide links here, which can be downloaded directly. This document includes the following annexes:)