Android software development basics and android software development

Android software development basics and android software development
1. android features: openness: a foundation of open source, convenience: Equality: 2. four basic components of Android are Activity, Service, Content Provider, and BroadcastReceiver. Activity is the most basic component in android. It is responsible for screen display, storage of UI controls, and direct interaction between content on Activity and users. An android project consists of multiple activities. The Service component runs on the system background without a UI screen. It serves to provide some services for the program. For example, download tasks, music playback, and data requests. There are also many services in the android system. Such as telephone service, short message service, GPS service, and WIFI service. The content provider of the ContentProvider component, which is used in android programs to share data between applications. There are many ways to save data in android programs, data sharing across applications is impossible without a unified standard, which is why ContentProvider exists. BroadcastReceiver component: the Broadcast mechanism is the basic mechanism for transmitting messages between applications in android. It registers Broadcast information such as phone, SMS, And WIFI on android phones. When a status changes, a broadcast is sent. We can use this component mechanism to capture various broadcasts for our program. 3. folder in the Android project: src Folder: Java source code; gen Folder: R. java file; assets Folder: resource file directory, which is not recorded by R; libs Folder: jar file on which the project depends; res Folder: resource file directory, which is recorded in R file; AndroidManifest. xml file: application configuration file; drawable Folder: image resource, drawable-hdpi: High Resolution storage (480*800) drawable-ldpi: low resolution storage (240*320) drawable-mdpi: Medium Resolution storage (320*480) drawable-xhdpi: higher resolution storage (1232*800) mipmap Folder: Stores image resources, similar to the drawable folder; layout Folder: place the layout file (xml file). Each Activity corresponds to an xml file. The values Folder: parameter value Directory, which contains the description of the xml parameter file. You can add strings, colors, and styles here. And so on.