Android is an operating system designed for mobile devices where mobile devices are devices that are characterized by the fact of having touch screens and sensors. An important characteristic of the Android operating system is that it is based on the Linux kernel. It is also powered by a Java-based virtual machine known as the Dalvik VM, which allows it to run applications.

Basic Architecture of Android

• APPs (top layer): Android apps are Java-based applications that are compiled into byte code, packaged, and installed on the Android platform.
• Application Framework (layer 2): The application framework is that layer that provides the services that are needed by Android apps to run such as the Window manager, the telephony manager, the location manager, and the resource managers and there are many more.
• Android Native Libraries (layer 3–1): The Android native libraries provide APIs for various functionalities. For example, the DB APIs (e.g. SQLite), the WebKit APIs, the SSL APIs, OpenGL, and so on.
• Android Runtime (layer 3–2): In addition to the libraries, the same layer also contains the Android runtime which consists of the Dalvik virtual machine which we just discussed, and also the core Java libraries. Basically, the core Java libraries are the Android version of the standard Java libraries, also called JDKs.
• Linux Kernel (basic layer): This is the core of the Android operating system, and it is a standard Linux kernel with some Google customizations that can be used to interact with hardware, as we previously stated.

The two most common programming languages used in Android app development are Java and XML. As a result, knowledge, and mastery of these programming languages are required to create an Android app. The following are some of the fundamentals of the Java programming language:

• Packages
• Objects & classes
• Inheritance & interfaces
• Strings & numbers, generics
• Collections
• Concurrency

A proper understanding of Java and XML will help you build/develop a more robust and elegant android app.

If you're new to Android app development, familiarising yourself with the build automation tools and the integrated development environment is critical before you start working on your app. For the tools, you can use Android app studio IDE or Eclipse; they will assist you in learning the basics as well as many other things that will help you improve your code. You can learn Apache Maven, Apache Ant, and Apache Gradle because they are powerful tools for managing your builds.

It is also important that you familiarize yourself with source control tools and concepts. Learn git and then create a git-source repository (by creating an account on Bitbucket or GitHub). To understand the basic concepts and terms of how the platform operates, you can use the Git Pocket Guide.

The Definition of Activities

A single screen with a user interface constitutes an activity (UI). A phone dialer, for example, is an activity. Here are a few more things to consider when it comes to activities:

• Independent Units: activities are independent units
• Coherence: activities can work together to form a cohesive wholes
• Invocable: activities can be invoked by other applications (i.e. invoke the camera)
• Extendable: we can create an activity by simply extending the activity class, which is part of the Android system

The Definition of Service

A service is an application component that performs a usually long-running operation in the background while not interacting with the user. It is a way for the app to tell the system about something that it wants to continue doing in the background, even when the user leaves the application. For example,

• a service for playing music
• a download service

Services, unlike activities, run in the background and do not interact with the user, so they do not have a UI. Creating a service is as simple as extending the service class, as it is with activities. Here are some of the most common applications for the services:

• a way for APPs to run in the background
• a way for applications to expose some of this functionality. By doing so, applications can bind to the service and use the service.

Application components are the essential building blocks of Android app development. Each of the components is a different point by which the system can enter your app. Although each one of them exists as its own entity and plays a specific role, there are some which depend on each other, and not all of them are actual entry points.
There are five different types of app components, each with its own purpose and life cycle that defines how they are created and destroyed. They are as follows:

• Activities:

This is a component that represents a single screen with a user interface (for instance, an email app may have one activity showing a list of new emails, another activity composing emails, and another one reading emails). Activities work together to form a cohesive user experience in the app. However, each one of them is independent.

• Services:

This is a background component that performs tasks for remote processes or long-running operations. It doesn't have a graphical user interface (for instance it might play music in the background while the user is in a different app).

• Content providers:

This is the component that manages a shared set of app data. Through this component, the data that you store either in the file system, on the web, an SQLite database can be queried or even modified (as long as the content provider allows it). This component is also useful for writing and reading data that is not shared and is private to your app.

• Broadcast receivers:

This component is responsible for responding to system-wide broadcast announcements. The system generates the majority of the broadcast receivers, and while they don't have a user interface, they can create a status bar notification that alerts the user when a broadcast event occurs. In general, it serves as a link to the other components and performs only minor tasks.

• Activating components:

The asynchronous message referred to as intent activates 3 of the 4 components (i.e. services, activities, and broadcast receivers). Intents also bind individual components to one another at runtime whether the component belongs to your app or not.

Types of Bindings

When we use intents, we are actually performing an action in one activity and starting another activity as a result. There are a variety of ways in which this can occur.

• Direct Binding for Activities: the activity or the app generating the intent will directly start an activity from another application
• Direct Binding for Services: the app generating the intent could directly start the service
• Broadcast: It could broadcast the event to all interested broadcaster receivers, depending on the activity that generated the intent.

Android is a fragmented market with many different devices and operating system versions. Note that, if your device supports more devices and/or versions it will definitely require more maintenance and testing as well as the related costs. The vice-versa is also true. You also require appropriate fonts, assets, and layouts that will help in ensuring that the best possible experiences in the various screen characteristics are given. You should also consider the array of android supported sensors or UI facilities. All android apps have an application class, one or more activities, and one or more fragments.

You may have services for background tasks that should run indefinitely at times, but you may not have them at other times. Always ensure that the thread is never blocked if you want to provide a great and smooth user interface. As a result, all long operations (computations, I/O, network, and so on) should be run in the background asynchronously (mainly on a different thread of execution). This is why understanding Java's concurrency features is crucial.

The simple tools that you need for Android app development are just a Mac or Windows PC, any type of Linux, and Eclipse, the ADT Plugin, and the Android SDK—all of which are free. You can go through the installation guide on Google to learn how to set up your development environment; it provides documentation of everything needed. Android has some unique parameters that you should consider when writing an Android app. Some of them include:

• Performance and responsiveness: You should always respond to user input within five seconds otherwise the operating system will ANR you. (ANR-application not responding – the only option that you will have is to force close your app.)
• Lags of more than 100ms will be noticed by the users: As mentioned above, the UI thread should never be blocked because it is only one.
• Limited resources: Wake-locks (the mechanism that forces the device to do a certain thing despite the recommendation to put the device to sleep by the battery manager) should be used sparingly. Do not unnecessarily poll hardware (e.g. GPS or accelerometer) because it will quickly run down the battery.

Check out our video that takes you through the introduction to Android Application Development to get a taste of what the course entails.

Android Activity Lifecycle

Because Android apps run in a multitasking environment, the runtime system routinely suspends, stops, and even kills applications and activities.

If you want an example, just think of the case of a phone call that arrives while you’re writing an email message. In such cases, what happens is that the phone application replaces your email client and gets in the forefront.

There's still a lot to learn, whether you decide to start with a simple app on your own or hire a top Android development firm to build a more robust solution. Consider what is best for your users and proceed from there.

Conclusion

Work on the fundamental Android apps first. Try to take in as much as you can from the experience and put your new skills to use. Look over some of the Android tutorial websites and get in touch with some of the game's experts. This will assist you in comprehending the overall app architecture and developing fantastic mobile applications.

CONTACT WE

Email   :[email protected]
Mobile :+91 99524 91705