Post by mitu on Oct 30, 2023 12:02:35 GMT
Android OS is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. It is developed by a consortium of developers known as the Open Handset Alliance, though its most widely used version is primarily developed by Google.
Android OS is a complex system, but it can be broadly divided into the following layers:
Linux kernel: The Linux kernel is the core of Android OS. It provides the basic functionality that all other layers rely on, such as memory management, process management, and device drivers.
Android Runtime (ART): The ART is a Java virtual machine (JVM) that is specifically designed for Android OS. It provides the environment in which Android applications run.
Android Framework: The Android Framework provides a set of APIs that developers can use to create Android applications. It includes classes for common tasks such as drawing graphics, interacting with the user, and accessing the device's hardware.
Applications: The top layer of Android OS is the applications layer. This is where users install and run their apps.
When a user opens an Android app, the following happens:
The app's code is loaded into the ART.
The ART creates a new process for the app.
The ART executes the app's code.
The app interacts with the Android Framework to access the device's hardware and services.
The app draws its graphics to the screen.
The Android OS also includes a number of other components, such as the mobile phone number listlink, which manages the lifecycle of applications, and the PackageManager, which installs and manages packages.
Here is a more detailed look at each layer of the Android OS:
Linux kernel
The Linux kernel is the core of Android OS. It provides the basic functionality that all other layers rely on, such as memory management, process management, and device drivers. The Linux kernel is also responsible for managing the device's hardware, such as the CPU, memory, and storage.
Android Runtime (ART)
The ART is a Java virtual machine (JVM) that is specifically designed for Android OS. It provides the environment in which Android applications run. The ART is responsible for loading, executing, and managing Android application code.
Android Framework
The Android Framework provides a set of APIs that developers can use to create Android applications. It includes classes for common tasks such as drawing graphics, interacting with the user, and accessing the device's hardware. The Android Framework also provides a number of standard services, such as the window manager, notification manager, and content provider.
Applications
The top layer of Android OS is the applications layer. This is where users install and run their apps. Android applications are typically written in the Java programming language, but they can also be written in other languages, such as C++ and Kotlin.
How Android OS manages applications
The Android OS manages applications using a number of different components, including the Activity Manager, the PackageManager, and the Service Manager.
The Activity Manager is responsible for managing the lifecycle of applications. It controls which applications are running and which applications are in the background. The Activity Manager also provides a number of APIs that developers can use to control the lifecycle of their applications.
The PackageManager is responsible for installing and managing packages. Packages are the files that make up an Android application. The PackageManager provides a number of APIs that developers can use to install, uninstall, and update packages.
The Service Manager is responsible for managing services. Services are background processes that can be used to perform tasks such as playing music or downloading data. The Service Manager provides a number of APIs that developers can use to create and manage services.
Conclusion
Android OS is a complex system, but it is also a very powerful one. It provides a rich set of APIs that developers can use to create innovative and user-friendly applications. Android OS is also a very flexible system, and it can be customized to meet the needs of different devices and users.
Android OS is a complex system, but it can be broadly divided into the following layers:
Linux kernel: The Linux kernel is the core of Android OS. It provides the basic functionality that all other layers rely on, such as memory management, process management, and device drivers.
Android Runtime (ART): The ART is a Java virtual machine (JVM) that is specifically designed for Android OS. It provides the environment in which Android applications run.
Android Framework: The Android Framework provides a set of APIs that developers can use to create Android applications. It includes classes for common tasks such as drawing graphics, interacting with the user, and accessing the device's hardware.
Applications: The top layer of Android OS is the applications layer. This is where users install and run their apps.
When a user opens an Android app, the following happens:
The app's code is loaded into the ART.
The ART creates a new process for the app.
The ART executes the app's code.
The app interacts with the Android Framework to access the device's hardware and services.
The app draws its graphics to the screen.
The Android OS also includes a number of other components, such as the mobile phone number listlink, which manages the lifecycle of applications, and the PackageManager, which installs and manages packages.
Here is a more detailed look at each layer of the Android OS:
Linux kernel
The Linux kernel is the core of Android OS. It provides the basic functionality that all other layers rely on, such as memory management, process management, and device drivers. The Linux kernel is also responsible for managing the device's hardware, such as the CPU, memory, and storage.
Android Runtime (ART)
The ART is a Java virtual machine (JVM) that is specifically designed for Android OS. It provides the environment in which Android applications run. The ART is responsible for loading, executing, and managing Android application code.
Android Framework
The Android Framework provides a set of APIs that developers can use to create Android applications. It includes classes for common tasks such as drawing graphics, interacting with the user, and accessing the device's hardware. The Android Framework also provides a number of standard services, such as the window manager, notification manager, and content provider.
Applications
The top layer of Android OS is the applications layer. This is where users install and run their apps. Android applications are typically written in the Java programming language, but they can also be written in other languages, such as C++ and Kotlin.
How Android OS manages applications
The Android OS manages applications using a number of different components, including the Activity Manager, the PackageManager, and the Service Manager.
The Activity Manager is responsible for managing the lifecycle of applications. It controls which applications are running and which applications are in the background. The Activity Manager also provides a number of APIs that developers can use to control the lifecycle of their applications.
The PackageManager is responsible for installing and managing packages. Packages are the files that make up an Android application. The PackageManager provides a number of APIs that developers can use to install, uninstall, and update packages.
The Service Manager is responsible for managing services. Services are background processes that can be used to perform tasks such as playing music or downloading data. The Service Manager provides a number of APIs that developers can use to create and manage services.
Conclusion
Android OS is a complex system, but it is also a very powerful one. It provides a rich set of APIs that developers can use to create innovative and user-friendly applications. Android OS is also a very flexible system, and it can be customized to meet the needs of different devices and users.