(User registration and login programs are already common in WEB development, and they are not difficult to implement. Now Android is popular. For example, how about implementing user login and registration on some android users or websites? In fact, it is as simple as Web development. As long as you see this complete example, I believe you will learn it. If you have a compilation environment, please recompile the project yourself, and then copy it to your mobile phone to run. You can see the effect. No more screenshots here. If you have just learned Android program development, you should have a look. This document includes the following annexes:)