Android API Guides Learning--introduction (1)

Android Introduction:

Android provides a rich application development framework that allows you to create unique applications and environments for mobile devices in the Java language environment.

1android applications provide multiple entry points

Android applications are composed of different components, each of which is called separately. The activity component provides a screen as the user's interface. The service is executed behind the scenes independently.

You can use the intent class to switch components. You can also call the same component multiple times in an app. For example, an activity component that displays an address in a map application. The model provides multiple entry points for a single application and allows any application to behave as a user's " default " action for other application calls

2 applications adapted to different devices

Android Services provides an adaptable application framework that allows you to use different resources on different device configurations. For example, it can create different XML layout files based on different screen sizes, and the system determines which layout the application creates based on the screen size of the current device.

If your application features require special hardware (such as a camera), you can query whether the device features are available during the application's run time. If necessary, you can announce that the app needs this feature in the App Store (for example, Google Play store). It also indicates that installation is not allowed if this feature is not supported.