Android developers create applications and software for Android devices and the Google Play Store. Apps created by this software developer run on Android smartphones and tablets. In tandem with the rapid growth of the Android market, job opportunities for Android developers also increase.
The most basic building block of Android development is a programming language. The most preferred languages to create Android apps are Kotlin and Java. You need to be familiar with the core concepts of one or both of these two programming languages, including basics and syntaxes, collection framework, concurrency and multithreading, generics and functional programming.
To design layouts (user interface) in Android, we use XML. Much like HTML, XML is also a markup language and stands for extensible Markup Language. After creation of these XML Layouts, they are linked to Kotlin/Java files where business logic is written.
To design seamless XML layouts and write business logic in an integrated environment, there exists a handy tool known as Android Studio. Android Studio uses Gradle, an advanced build toolkit, to automate and manage your build process. To integrate Gradle in Android studio there exists a plugin known as the Android plugin for Gradle. Before you get started, you need to understand what Gradle is and how to use it specifically for managing external dependencies.
Gradle and Android plugin run independently of Android Studio. This means you can build your Android apps from within Android Studio, the command line on your machine, or on machines where Android Studio is not installed (such as continuous integration servers). If you are not using Android Studio, you can learn how to build and run your app from the command line.
User interaction with Android apps should be considered with utmost priority. Responding to events by using callbacks, implementing appropriate gestures such as drag and drop, providing right keyboard for user input and using pan and zoom in the right place plays a crucial role in providing the seamless user experience. These are really small but very useful in improving user interaction. Above all, this user interactivity takes place in an Android component known as Activity.
An Activity is a single, focused thing that the user can do. Almost all Activities interact with the user, so the Activity class takes care of creating a window for you in which you can place your user interface.
The Android device comes with various screen configurations. Screen orientation is one of them. It can be either portrait or landscape. Each Activity can exist in either portrait or landscape mode. When the screen is rotated the current activity is destroyed and recreated in a new orientation. The stability of an Activity should always be maintained when screen orientation changes.
An application is incomplete if it lacks modern UI. An application may contain useful functionalities, but if it fails to adapt to modern UI guidelines, then it is ultimately doomed to fail. Using Recycler View to implement lists and grids, using Constraint Layout for designing complex layouts, applying animations to enhance user experience, using appropriate menus, following Material design guidelines and using vector drivable instead of raster graphics are a few of the basic rules that every developer must follow in their apps. While designing layouts one must not forget to consider the multiple screen type devices. The same app should look different for different devices. For example, the screen on a tablet should show dual-pane layouts to effectively utilize a widescreen. While on a smartphone it should use single pane. This behavior can be achieved by using Fragments. Additionally, in several cases, you might need to customize Views that suit your need. This can be achieved by designing custom components for your Views.
Navigation refers to the interactions that allow users to navigate across, into and back out from the different pieces of content within your app. There are various UI elements that allow you to implement effective UI navigation.
The most basic one is the app bar which is popularly known as Toolbar. On your Toolbar, you can add a popup menu, menu icons and add a navigation drawer icon. This navigation drawer icon helps you to open and close the navigation drawer which is another element to implement effective navigation. The navigation drawer allows you to add additional menu items which can help you to swap fragments in your current Activity or perform some other relevant actions.
Another navigation element is a BottomNavigationView which allows you to switch between different Fragments in the same Activity by using tabs at the bottom of the screen. If you need to use tabs attached to the Toolbar and swipe between Fragments (different pages), then ViewPager should be your choice.
User intention is the most important aspect of navigation. The user might want to launch new Activity, move back to the previous Activity or even share data to some other app. These intentions can be achieved by using Intents in Android. If you know your target Activity use Explicit Intent otherwise use Implicit Intents. You are always allowed to configure your intents.
Above all, Android Jetpack's Navigation component helps you implement navigation, from simple button clicks to more complex patterns, such as app bars and the navigation drawer. You might want to take a look at this component before you start implementing navigation in Android.
Users interact with your app on a variety of levels, from pressing a Submit button to downloading information onto their device. Accordingly, you should test a variety of use cases and interactions as you iteratively develop your app. The most commonly used testing libraries are Expresso, Junit, Mockito, Robolectric and UI Automator.
Data is an important part of your application and must not be ignored. You may need to fetch data from the server, query data from the local database, save user preferences and do file handling.
To use local database, use Room database, which is the part of Android Jetpack's architecture component. You might want to share your database outside your app securely using ContentProvider.
To save a small amount of data such as key-value pairs or typed objects you can use Jetpack’s Data Store, which uses Kotlin coroutines and Flow to store data.
If you want to bind your UI components in your layouts to a data source in your app using a declarative format, use Data Binding Library.
To handle files in your app, you can take advantage of massive file system APIs provided to you.
Above all, to access the data over network (i.e. while consuming REST APIs), use Retrofit 2 libraries, which is a blessing from Jake Wharton to all Android developers.
Notifications are one of the best ways to increase user engagement. It appears outside of your app's UI to provide the user with reminders, communication from other people or other timely information from your app. Users can tap the notification to open your app or take an action directly from the notification. You can create a notification, customize its layout, add action to it and even group multiple Notifications using Notification channels.
If you hate being a backend developer, Firebase on Android is the way for you. Firebase is a mobile platform that helps you quickly develop high-quality apps, grow your user base and earn more money. Firebase provides several utility features to make the life of an Android developer easy.
To make your app visible in Google search you can use Firebase App Indexing API. You can use cloud storage and cloud firestore to store data in your server. If you need to automatically run backend code in response to events triggered by Firebase features and HTTPS requests, use Cloud Functions. Next is the Firebase Cloud Messaging (FCM) that lets you push notifications to your clients. Using FCM, you can notify a client app that new email or other data is available to sync. Use Firebase Crashlytics, which is a lightweight, real-time crash reporter that helps you prioritize and fix stability issues. If you have ever used deep links in your app, try Dynamic links. With Dynamic Links, your users get the best available experience for the platform they open your link on.
You might want to take a look at other Firebase features, such as Firebase Invites, Firebase Performance Monitoring, Firebase Remote Config, Remote Config and A/B Testing.
Android has built-in security features that significantly reduce the frequency and impact of application security issues. You can protect the user's privacy by using permissions. Share data securely by using signature-based permissions. Handle data security by using internal storage, external storage and ContentProviders very cautiously. By default, never export your Android component, such as ContentProvider, Service or BroadcastReceiver, unless you need to.
Git is free and open-source software used for version control. Git lets you experiment with new application features and coding techniques with confidence. You can work on new crazy ideas for your project while your previous working copy stays safe and secure. The moment you may realize you are evolving your project in the wrong direction, you can restore your previous version, hassle-free and course correct.
As the world moves ever more into the mobile landscape, Android app developers can be sure to find an audience for their creations, or bring great value to companies in need of mobile app development skills.
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