(Hello World, are you familiar with programming? If you don't know whether you are ASP/PHP or VB/VC, if you read some professional books related to this, you will almost mention the HelloWorld program, which will lead you to understand the art palace of their respective programming languages. This code is related to Android phone programming. It runs in the Java environment. Recently, Android phone software development has been very popular. I hope this small model can help you. This document includes the following annexes:)