This article marks the beginning of a new topic on the Android Emotions and has the objective of who read these articles gets the knowledge on how to develop in Android
In this series of tutorials, the tool used to develop will be Android Studio, and they will be based on the Android 5.0 Lollipop.
Over the time, these tutorials will be updated according to the new operating system versions that are being released.
Before we start looking at code, we must first know what really is Android. Most of you, when begin to read this tutorial, think to know Android completely , even so, we’ll give you just a few more tips.
The Android Operating System
Android is an operating system based on Linux. The name of the project that is responsible for the development of Android is called Android Open Source Project (AOSP) and is led by Google.
This operating system supports background processing, provides an interface library very rich, supports 2D and 3D graphics (using OpenGL-ES library, better known by OpenGL), allows access to the file system as it has incorporated the database SQLite .
An Android application typically consists of several components, visual ones, other non-visual, and we can use components of other applications.
In Android, as mentioned earlier, we can use other applications components. An application , that we are developing, can access other applications in order to accomplish a “task”. This is quite important because it allows us to develop an application in a simpler way and let us to reuse things that already exist. For example, in our application, we have a button that starts the application of photo management (photo album of our mobile phone) that allows us to choose a specific photo and back to our application later. It means that our application uses a task, which is basically to use a external functionality to our application, which turns out to complete it.
Android platform components
The Android OS is divided into several layers, and these can be divided into four areas as shown in below:
The levels can be described as:
- Applications: the AOSP project contains several default applications, such as browser, camera, gallery, music application, a telephone, and many other;
- Framework: an API that enables applications to interact with the Android OS;
- Libraries / Runtime: libraries for many of the major features (for example, render graphics, data storage, web browsing, etc.). In this area,, are also the tools to perform in real time applications and the operation of the operating system, such as Dalvik and Java libraries;
- Linux Kernel: responsible for communicating the Android operating system with the hardware.
The two bottom layers, that is Libraries / runtime and Linux Kernel, are encapsulated by the Framework layer. This means that typically a programmer will work only with two layers: the application and the framework.
A separate chapter for Google Play, because this is where developers can put their applications available for the millions of Android users worldwide.
Android users use the Google Play Store to purchase and install the applications that will be made by us, programmers.
But beyond being important to the user to buy and install the application (after all that is where we make money), it is also through the Google Play Store that we may provide updates to the same. If a programmer upload a new version of the application, users will receive an automatic notification of the existence of an update, letting them choose whether or not to install this new update.
In the next article we will have the opportunity to talk about the tools for developing Android.
Note: Tutorial made by João Mateus in android-emotions.pt and translated by Adriana Afonso