Key concepts of Android application development
Android is an open source mobile platform launched by Google in 2008 and has since become a favorite among people and developers around the world. Android is a multi-threaded and multi-threaded operating system based on Linux. Google’s Android operating system is not limited to phones, but you can use it to build a DVR, handheld GPS, MP3 player, etc.
Although the Android platform is open source and customizable, Android users and developers have become common in the builds developed by Google for Android devices. Using these Android concepts is vital to developing an application quickly.
The key concepts of Android are: –
Apps and APK files
Activities
Fragments
Views and view groups
XML file layout
Intentions
Widgets
Services
Sensors
I am giving you an overview of the key concepts of Android. After you have a basic understanding of the key Android concepts, you can delve into the different topics.
Apps and APK files
An Android application is an Android application. An application is packaged in an APK file, that is, an Android application package. The APK file contains the compiled Java code and other resources such as images and texts for the Android application
Activities
An Android activity is a GUI component. You can understand it as a window in a desktop application. Since mobile phone screens are small, one activity fills the entire screen. If you open multiple activities, they are stacked on top of each other. You can’t organize activities side by side like you can with desktop windows.
Activities are unique and specific actions that a user can perform. Since it is difficult to scroll, zoom, or click links on a small screen, it is recommended that an application display only one activity per screen. This will present the most relevant information to the user and allow them to open a new screen for additional information or click the Back button to view the previous activity. The screen can display multiple tasks, but it should help the user to complete only one activity at a time.
Fragments
On Android, a snippet is a snippet of a total user interface. A fragment only takes up part of the screen. Fragments are used in activities. The fragments can also be used in different activities. Fragments contain views and view groups within them.
View and view groups
The Android GUI items are divided into three categories, namely Activities, Views, and View Groups. The activities are the windows / screens. Views are the individual elements of the GUI, such as a TextView that displays text, a button that users can click, and so on. ViewGroups are containers for Views. A ViewGroup actually groups a collection of Views. Views and view groups can be nested within an activity or even within a fragment that is nested within an activity.
XML file layout
View groups, snippets, and activities can use XML files to define their layout and content. Layout XML files indicate which GUI components an activity or fragment contains and also the style of the GUI components, that is, size, margins, padding, and so on.
Intention
If your application requires to perform a function beyond its core capabilities, such as opening a photo, playing a video, or searching for a contact, then you need to find out if a tool that can perform that function already exists in the operating system or in a third-party application. . If yes, you can get the benefit of that functionality by using intents.
For example, if your application accesses the user’s contacts, you can use intent objects to launch the existing Contacts application on the device. This eliminates scheduling duplication and also speeds up user interaction with the device as the user will not need to learn again how to add a contact to your application.
Widgets
Android widgets are actually GUI components that can be displayed outside of an activity. For example, a weather widget that shows today’s weather is displayed on many Android home screens. The widgets have been packaged and implemented as part of an Android application. Also sometimes, Views in Android are also known as widgets. For example, many GUI components are placed in a Java package called android.widget. The GUI components are not the same as a widget that can remain on the home screen of an Android device. So you need to understand the difference between GUI components that can be used within ViewGroups, Fragments and components that can be used within ViewGroups, Fragments and Activities and also within Widgets and Widgets that can remain on the home screen of the Android device.
Services
On Android, services are background processes that can run on an Android device even if no app is visible. The services do not require a user interface. For example, a service can check a remote server for updates or backup data every hour.
Sensors
Android devices have a lot of built-in sensors that you can access from your Android apps. For example, the built-in GPS in smartphones is a sensor. Hence, you can access GPS from within your Android apps.