The role of Android Activiy

In Android applications, the activity is primarily responsible for creating windows, and a activicy represents a separate screen and is the only thing the user can see

That is, activity is used to implement and user interaction, and the view layer inside. NET MVC is the same meaning and the model layer in the three-tier architecture.

Activity life cycle: activity in a total of four states are: active or running state, activity running in the front of the screen

<LinearLayout>

</LinearLayout>

This is used in a linear way to layout. @string/hello represents the Strings.xml file name referenced in the project Res/values directory

Name is a string of Hello,

The role of Android Activiy