Android app development

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 Application Development Tools and Environment

If you are stepping into Android App development, 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 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 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 acceler ometer) 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 app development