Android App Development Fundamentals

What is Android?

You must have heard of it – or perhaps having it in your hands right now! About 85% of the devices sold use Android as their OS.

Android is a popular mobile operating system developed by Google. Most of the popular phones like Samsung, Google Nexus, Sony Xperia are based on Android. Android is an open-source i.e.; the OS can be customized by developers depending on the handset.

Android is based on Linux Kernel. Android programs are written in Java using ASDK (Android Software Development Kit) and run through the Java Virtual Machine (JVM) optimized for mobile.

Benefits and Features of Android

Android is one of the most widely used OS, and there are lots of applications that can be downloaded from the Google play store other than the built-in applications that come with the phone. Some features and benefits of Android are:

• Open source and free – easy for small businesses to develop their choice of apps
• Huge community and support
• Rich development environment
• Very cost-effective to develop apps
• Intuitive UI
• Wide connectivity options.
• Extensive support for media files format.
• Data storage using SQLite
• Resizable widgets
• Multi-touch and multitasking

     In the Android Developer Fundamentals course, you learn basic Android programming concepts and build a variety of apps, using the Java programming language. You start with Hello World and work your way up to apps that schedule jobs, update settings, and use Android Architecture Components.

About the course :

The Android Developer Fundamentals course was created by the Google Developers Training team. To take the course, you must have experience with the Java programming language.

The course materials include:

• Codelabs with suggested homework assignments: Codelabs for Android Developer Fundamentals
• Concept reference chapters: Android Developer Fundamentals — Concepts
• Slide decks
• Source code in GitHub for starter apps and solution code for apps that you create in the codelabs

Each lesson contains a slide deck, a concepts chapter, and in most cases, one or more codelabs. As you work through the codelabs, you create apps as a way to practice and perfect the skills you’re learning. Some lessons are purely conceptual and don’t have codelabs.

The materials are freely available online for use by instructors, or for self-study by anyone who knows the Java programming language.

Android Developer Fundamentals prepares you to take the exam for the Associate Android Developer certification.

What does the course cover?

The course includes four teaching units, each of which includes several lessons:

• Unit 1: Get started
• Unit 2: User experience
• Unit 3: Working in the background
• Unit 4: Saving user data

Unit 1: Get started :

This unit covers installing Android Studio, understanding project structure, building your first app, creating activities, testing your apps, and using the Android Support Library.

First, you deploy a simple Hello World app. You go on to create an app with a simple activity, and then you create a multi-screen app that passes data between activities. You also learn how to use the Android Support Library to provide backward-compatibility with earlier versions of the Android system for your app.

Unit 2: User experience :

This unit covers how to get input from the user, implement navigation strategies, use themes and styles, test your user interface, and follow Material Design principles.

You create apps that use menus and tabs for navigation, and input controls such as spinners and picker dialogs to get information from the user. You learn how to extract resources to create a style from an instance of a user interface element. You write an app that displays a word list in a recycler view (and you learn why it’s better to use a recycler view than a plain scrolling list).

You also build a score-keeping app to explore Material Design guidelines.

Unit 3: Working in the background :

This unit covers how to do background work, how to schedule tasks, and how to trigger events. It covers the performance implications of executing work in the background, as well as best practices for reducing battery drain. You learn how Android determines which apps to keep running and which to stop when resources run low.

You write an app that connects to the Internet in a background thread to find the author of any book. You also build apps that send notifications and schedule tasks, and you learn how to implement scheduling functionality for apps that run on earlier versions of Android.

Unit 4: Saving user data :

This unit discusses how to store user data. You learn how to use shared preferences to save simple key value pairs, then you learn how to use the Room database to save, retrieve, and update user data. This unit also introduces you to the Android Architecture Components, which represent best practices for structuring your app.

1. Master the Language

Java and XML are the two main programming languages used in Android App development. Knowledge and mastery over these programming languages are, therefore, prerequisites to developing an Android app. Some of the fundamentals of the Java programming language include:

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

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

2. Familiarity with the Right Development Tools and Environment

It is very important that you familiarize yourself with the build automation tools as well as the integrated development environment before you start developing your app. You can use Android app studio IDE or the Eclipse for the tools; they will help you learn the basics and many other things that will help improve your code. You can learn Apache Maven, Apache Ant, and Gradle as they provide a powerful set of tools to help in managing your builds.

It is also important that you familiarize yourself with source control tools and concepts. Learn the 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.

3. Knowledge of the Application Components

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 serving a distinct purpose with a distinct life cycle which defines how it is created and destroyed. They include:

• 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 component that runs in the background to perform work for remote processes or long-running operations. It does not provide a 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 is the component that responds to system-wide broadcast announcements. Most of the broadcast receivers originate from the system, and although they do not display a user interface, they can create a status bar notification that alerts the user when a broadcast event occurs. Generally, it is a gateway to the other components and it only does minimal work.
• Activating components: A synchronous 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.

4. Awareness over Fragmentations, Android Application, Threads, Loaders and Tasks

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.

Sometimes, you may have services for background tasks that should run continuously but other times you may not. If you want to deliver a great and smooth user interface, always ensure that the thread is never blocked. Therefore, the long operations (computations, I/O, network, etc.) should all be run asynchronously in the background (mainly on a different thread of execution). This is why it is important to learn the Java language concurrency facilities.

5. Making the Right Choice over Needed Tools

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.

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Conclusion

77% of Americans today own a smartphone,  and apps are where the majority of their time is spent. In fact, in 2017, 197 billion apps were downloaded, ensuring that a career as an Android App Developer is a stable one with lots of opportunity for growth. There’s a lot to learn, so consider getting started with Simplilearn’s Google-authorized Certified Android App Developer training course. You’ll learn to master Android fundamentals along with the other skills you need with hands-on experience, developing six trending applications during the course. The course is aligned with the Associate Android Developer (AAD) Exam conducted by Google. Happy app-developing!