设计一个主Activity和一个子Activity（Sub-Activity），使用主Activity上的按钮启动子Activity，并将子Activity的一些信息返回给主Activity，并显示在主Activity上，可以自己设计界面和场景，。主Activity界面上有一个“登录”按钮和一个用了显示信息的TextView，点击“登录”按钮后打开一个新的Activity，新Activity上面有输入用户名和密码的控件，在用户关闭这个Activity后，将用户输入的用户名和密码传递到主Activity，并显示在主Activity的TextView中。
React
A declarative, efficient, and flexible JavaScript library for building user interfaces.
🖖 Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.
Typescript
TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
An Open Source Machine Learning Framework for Everyone
Django
The Web framework for perfectionists with deadlines.
Laravel
A PHP framework for web artisans
Bring data to life with SVG, Canvas and HTML. 📊📈🎉
JavaScript (JS) is a lightweight interpreted programming language with first-class functions.
Some thing interesting about web. New door for the world.
A server is a program made to process requests and deliver data to clients.
Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.
Some thing interesting about visualization, use data art
Some thing interesting about game, make everyone happy.
Facebook
We are working to build community through open source technology. NB: members must have two-factor auth.
Microsoft
Open source projects and samples from Microsoft.
Google
Google ❤️ Open Source for everyone.
Alibaba
Alibaba Open Source for everyone
D3
Data-Driven Documents codes.
Tencent
China tencent open source team.
