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So far in this course, steps have been taken to set up an environment suitable for the development

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of Android applications using Android studio.

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An initial step has also been taken into the process of application development through the creation

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of Android Studio Application Project.

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Before delving further into practical matters of Android application development, however, it is important

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to gain an understanding of some of the more abstract concepts of both Android software development

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kit and Android development in general.

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Gaining a clear understanding of these concepts now will provide a sound foundation on which to build

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further knowledge.

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So starting with an overview of Android of Android application in this course and continuing to in the

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next few lectures of this course, the goal is to provide a detailed overview of the fundamentals of

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Android development.

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My name is Stephan and let's get started with our lecture.

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The Android software stack on Android is a structured in the form of software stack comprising applications

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and operating systems, runtime, environment, middleware services and libraries.

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This architecture can perhaps can best be represented visually as outlined in this screenshot.

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Each layer of the stack and the corresponding elements within each layer are tightly integrated and

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carefully tuned to provide the optimal application, development and execution environment for mobile

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devices.

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The remainder of this course will work through the different layers of this Android stack and starting

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the bottom with the Linux kernel.

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So let's get started with the Linux kernel.

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Linux kernel positioned at the bottom of Android software stack.

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The Linux kernel provides a level of abstraction between the device hardware and upper layers of Android

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software stack based on Linux version 2.6.

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The kernel provides a preemptive multitasking, low level core system services such as memory process

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and power management.

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In addition to providing a network stack and device drivers for hardware such as device displays, WiFi

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and audio.

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The original Linux kernel was developed by in 1991 by Linus Torvalds and was combined with a set of

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tools, utilities and compilers developed by Richard Stallman at the Free Software Foundation to create

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a full operating system referred to as Genie or Linux.

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The various Linux distributions have been derived from the basic underpinnings such as Ubuntu and Red

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Hat Enterprise Linux.

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The Kali Linux and the Ubuntu and other Linux based systems.

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And it's important to note, however, that Android uses only the Linux kernel.

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That said, it is worth noting that the Linux kernel was originally developed for use in traditional

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computers in the form of desktops and servers.

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In fact, Linux is now most widely deployed in mission critical enterprise server environments and it

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is a testament to both the power of today's mobile devices and the efficiency and performance of the

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Linux kernel that we find this software at the heart of the Android software stack.

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In addition to a set of standard Java Kotlin Development libraries, this providing a support for such

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general purpose tasks such as string handling, networking and file manipulation.

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The Android development environment also includes the Android libraries.

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These are a set of Java based libraries that are specific to Android development.

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Examples of libraries in this category include the application framework libraries in addition to those

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that facilitate user interface building, graphics, drawing and database access.

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And on the screen you are seeing some of the most used libraries in Android.

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The Android runtime.

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Core libraries, as outlined in the preceding section, are Java and Kotlin based and provide the primary

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APIs for developers writing Android application.

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And it's important to note that, however, that the core libraries do not perform much of the actual

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work and are in fact essentially Java and Kotlin wrappers around a set of C and C plus plus based libraries.

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So when making a calls, for example, the Android OpenGL library to drive 3D graphics on the device

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display and the library actually ultimately makes a call to the OpenGL s C plus plus library, which

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in turn works with the underlying Linux kernel to perform the driving tasks.

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The C plus plus libraries are included to fulfill a wide and diverse range of functions, including

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2D and 3D graphics drawing secure sockets, layer, SSL communication, SQLite database management,

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audio and video playback bitmap and vector font rendering display subsystem and graphics layer management

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and an implementation of the standard C System library.

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This means the lib C here.

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So in practice, the typical Android application developer will access these libraries solely through

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Java or Kotlin based Android core library APIs.

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In the event that direct access to these libraries is needed, this can be achieved using the Android

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Native Development kit in the UK.

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So the purpose of which is to call the native methods of Non-java or Kotlin programming languages such

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as C and C plus plus from within the Java and Kotlin code using the Java Native interface G and I.

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And lastly, we have left to discuss the application framework in Android architecture.

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The application framework is a set of services that collectively form the environment in which applications

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and other applications run and are merged.

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This framework implements the concepts that Android applications are constructed from a reusable, interchangeable

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and replaceable components, and this concept is taken a step further in that an application is also

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able to publish its capabilities along with any corresponding data so that they can be found and reused

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by other applications.

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So they are following.

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The Android framework includes, for example, activity manager, which you can see on the screen here.

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So the applications here located at the top of the Android software stack are the applications.

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So these comprise both the native applications provided with the particular Android implementations,

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for example, web browser and the email applications and the third party applications installed by the

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user after processing the device.

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A good Android Development Knowledge Foundation requires an understanding of the overall architecture

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of Android.

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Android is implemented in the form of software stack architecture, consisting of a Linux kernel, a

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runtime environment and corresponding libraries, an application framework and a set of applications.

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So applications are predominantly written in Java or Kotlin and compiled down to bytecode format within

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the Android studio build environment.

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When an application is subsequently installed on a device, this byte code is compiled down by the Android

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runtime art to the native format used by the CPU.

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The key goals of the Android architecture are performance and efficiency, so both in application execution

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and the implementation of reuse in application design.