Android is an open source and Linux-based Operating System for mobile devices such as smartphones and tablet computers. Android was developed by the Open Handset Alliance, led by Google, and other companies.
Android offers a unified approach to application development for mobile devices which means developers need only develop for Android, and their applications should be able to run on different devices powered by Android.
The first beta version of the Android Software Development Kit (SDK) was released by Google in 2007 where as the first commercial version, Android 1.0, was released in September 2008.
On June 27, 2012, at the Google I/O conference, Google announced the next Android version, 4.1 Jelly Bean. Jelly Bean is an incremental update, with the primary aim of improving the user interface, both in terms of functionality and performance.
The source code for Android is available under free and open source software licenses. Google publishes most of the code under the Apache License version 2.0 and the rest, Linux kernel changes, under the GNU General Public License version 2.
Why Android ?
Features of Android
Android is a powerful operating system competing with Apple 4GS and supports great features. Few of them are listed below −
Sr.No.
Feature & Description
1
Android OS basic screen provides a beautiful and intuitive user interface.
Based on the open-source WebKit layout engine, coupled with Chrome’s V8 JavaScript engine supporting HTML5 and CSS3.
Android has native support for multi-touch which was initially made available in handsets such as the HTC Hero.
User can jump from one task to another and same time various application can run simultaneously.
Widgets are resizable, so users can expand them to show more content or shrink them to save space.
Supports single direction and bi-directional text.
Google Cloud Messaging (GCM) is a service that lets developers send short message data to their users on Android devices, without needing a proprietary sync solution.
A technology that lets apps discover and pair directly, over a high-bandwidth peer-to-peer connection.
A popular NFC-based technology that lets users instantly share, just by touching two NFC-enabled phones together.
Android Applications
Android applications are usually developed in the Java language using the Android Software Development Kit.
Once developed, Android applications can be packaged easily and sold out either through a store such as Google Play, SlideME, Opera Mobile Store, Mobango, F-droid and the Amazon Appstore.
Android powers hundreds of millions of mobile devices in more than 190 countries around the world. It’s the largest installed base of any mobile platform and growing fast. Every day more than 1 million new Android devices are activated worldwide.
This tutorial has been written with an aim to teach you how to develop and package Android application. We will start from environment setup for Android application programming and then drill down to look into various aspects of Android applications.
Categories of Android applications
There are many android applications in the market. The top categories are −
History of Android
The code names of android ranges from A to N currently, such as Aestro, Blender, Cupcake, Donut, Eclair, Froyo, Gingerbread, Honeycomb, Ice Cream Sandwitch, Jelly Bean, KitKat, Lollipop and Marshmallow. Let’s understand the android history in a sequence.
What is API level?
API Level is an integer value that uniquely identifies the framework API revision offered by a version of the Android platform.
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Android Application Class
W hile Starting App development, we tend to miss out simple basic stuffs either by ignorance or by curiosity to build million dollar app. But, Hey! Why so serious !. Building a App is bit of Art ,bit of Engineering and frequently both.
Activity Life Cycle is stages of activity in run time, knowing these would save you from headaches while you dive deeper in development.
I have written a post that will help you to understand activity lifecycle in a practical approach. Check it out
Android Activity Lifecycle
Android activity lifecycle is first thing to be known as android developer. Here I’m sharing with you some facts and…
Application class is a base class of Android app containing components like Activities and Services. Application or its sub classes are instantiated before all the activities or any other application objects have been created in Android app.
You Don’t have to import or extend application class, they are predefined. We cannot change application class but we could give additional instruction to it by extending it. Refer here for more info.
Create a java class named SubApplication and Application as Superclass
By extending Application class you could get boilerplate code like this
Check in AndroidManifest.xml and set Application name to SubApplication that you created
Lets take a situation where we should know which activity is currently running and we have to use register network receiver in all our activities. To this we used to write same code in all the activities or write a base class and extend that class instead of extending AppCompactActivity.
We have Activity Life cycle in one hand and Application class in another, what sense they make? Well actually they do? Let’s look into it.
In application class create static Activity variable it is accessible from whole project.
2. Register Activity Life Cycle callback in onCreate method in application class. By this step we can get currently running activity in our app from mActivity.
3.Moving on to next, Create a Broadcast Receiver and write a method to check the internet connection. you can get the code here .
4. Register your broadcast receiver in Manifest File
But for SDK Above Nougat we need to register receiver and unregister in every activity we use programmatically or We can just register and unregister Commonly in Application class.
5. Create a Object for Broadcast Receiver in application class and Register it in onResume method and Unregister in onPause method.
Bit confused! Don’t Worry, Here is the Link to the files.
Thanks for reading out the article. Let me know if I have missed out something interesting so that I can be added. Be sure to clap/recommend as much as you can and also share with your friends.
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Android From Scratch: An Overview of Android Application Development
Introduction
As of early 2016, there are well over a billion people actively using Android, a Unix-like mobile operating system that runs on phones, tablets, smart TVs, smart watches, and a slew of other devices. Although developed and maintained by Google, it’s free and open source software that can be used and customized by anybody. As a result, Android devices are manufactured by several major device manufactures, like Samsung, LG, Sony, and HTC.
One of the primary factors that drives Android’s success is Google Play, an Android app distribution platform users can use to download and install apps on their devices. With over a million apps and billions of downloads, Google Play is larger and sees more traffic than similar platforms for iOS and Windows 10.
I’m sure you are now beginning to wonder how you can become an app developer and cash in on the popularity of Android. In this article, I’m going to give you a bird’s eye view of what Android application development entails today.
Do you find it easier to learn with video? Why not check out our course:
Developing Native Android Apps
There are many different approaches to Android application development. In this series, however, we’ll be focussing only on the native approach because native apps offer superior performance, run with minimal overhead, and are capable of making the best use of the Android operating system’s capabilities.
Native Android apps are developed using the Java programming language, and, on devices running Android 5.0 or higher, make use of a managed runtime called Android Runtime (ART) by default. To create such apps, most developers choose to use Android Studio, the official Android IDE developed by Google. Android Studio is free and runs on Windows, OS X, and most Linux distributions.
Android Studio 1.5.1, the current stable release, has a large number of features to simplify all aspects of Android app development, such as a powerful code editor, visual layout and theme editors, vector and image asset studios, and more. Android Studio 2.0, which is still only available as a preview release, has more advanced features like instant run and a GPU profiler to further improve the app development experience.
Android Studio also comes with a realistic emulator you can use if you do not own an Android device. Because system images for it are freely available, you can download and run any version of Android on it.
Challenges Android App Developers Face
Developing an Android app that runs well on one specific Android phone or tablet is easy. Developing one that runs well on all Android devices, however, can be incredibly hard because of the vast differences in operating system versions, screen sizes, and device capabilities.
Supporting Older Android Versions
Unlike Apple’s iOS devices, most Android devices rarely receive software updates, if at all. Marshmallow, the latest version of Android, runs on less than 1.5% of all Android devices today, even though it was released several months ago.
This means, if you decide to develop an app, you must support older versions of Android, like KitKat and Lollipop. Moreover, if your primary user base is from developing countries, supporting older versions all the way back to Android Gingerbread, is recommended. Doing so, however, is usually easy, thanks to not only the Android Support Library, but also a number of third party open source libraries.
Handling Different Screen Sizes and Densities
In the early days of Android, there were only a small number of devices that could run Android and almost all of them were phones. Over the years, however, with more and more device manufacturers adopting the platform, device screen sizes and pixel densities began to vary wildly.
With the release of Android Honeycomb, Android also started supporting large screen devices, such as tablets and smart TVs. Consequently, developers today are expected to use multiple image sizes and layouts to support all those different screens.
While creating the layouts is still a rather time-consuming process, managing different image sizes has become easier thanks to Vector Asset Studio .
Handling Hardware Sensor Availability
Only a few high-end devices have all the hardware sensors the Android SDK supports. Therefore, developers are expected to write apps that can determine the hardware capabilities of a device at runtime, and degrade gracefully if possible.
The Android SDK (Software Development Kit) has a Sensor Framework to simplify this task. Alternatively, developers can prevent users from installing apps on devices missing the required hardware using Google Play filters.
Recent Trends
The Android platform is constantly evolving and app developers must keep up with recent trends to be able to build apps that live up to user expectations.
Material Design
Material design is a collection of well-thought-out design guidelines you can follow to build apps whose look and feel matches the native look and feel of Android Lollipop and Marshmallow. Owing to its simplicity and modern looks, material design enjoys a lot of popularity among both developers and designers.
Android Wear
Android Wear smartwatches are becoming increasingly popular because the latest models are better looking and have features, such as new and improved gestures and watch faces that make them more fun to use. Consequently, more and more developers are using the Wear API in their apps to make sure that their apps can interact with wearable devices.
Publishing Android Apps
Once you’ve developed an app, you can publish it online so that people all over the world can download and use it. There are lots of Android app marketplaces you can publish your app on, but the one most popular today is Google Play because it comes pre-installed on most Android devices.
To be able to publish your app on Google Play, you must pay a registration fee of $25 and create a developer account on it. Once you have an account, publishing an app involves uploading its APK—a compressed package file that you generate using Android Studio—along with a few screenshots and providing details, such as the app’s name and description.
After submitting all the details, you will have to wait for a few hours for the app to go live. In early 2015, Google Play introduced an app approval process to make sure that published apps adhere to Google’s content policies.
Monetizing Android Apps
Android app development is fun and nothing beats the rush you get seeing your app live on Google Play. However, if you’ve put in a lot of effort building the app, why not monetize it? A lot of people today make a living developing Android apps, and if your apps are good enough, you can too.
There are many ways you can monetize an app. Here are three popular ways, all of which use services provided by Google:
Sell It on Google Play: In most countries, developers are allowed to publish premium apps on Google Play. Unlike free apps, a premium app can only be downloaded after the user pays for it. This is the easiest way to monetize an app because you don’t have to write any code for it.
Display Advertisements: By using Google’s Mobile Ads SDK, you can display banner or interstitial ads in your app. With this setup, you are usually paid every time a user sees an ad or clicks one.
Sell Items Inside the App: By using the In-app Billing API, you can sell digital items to users who are already using your app. For example, you could make your app free and then charge a small fee to unlock a special feature in it. This type of apps are often called freemium apps.
Conclusion
I hope you now have a general understanding of what Android app development means today. Despite all its challenges, Android app development is quite easy because of the extensive documentation available online and the constantly improving development tools.
In the next post of this series, you are going to take your first step towards becoming an Android app developer by learning how to set up Android Studio on your computer.
