Setting Up And Getting Started With Android Studio
Go to this link and install the latest JDK. Now download the Android Studio and SDK tools bundle from here. Install the Android Studio and SDK following the set up. Keep note of the SDK location. If you face any errors go to settings later to resolve them.
Lastly, learn to integrate 3rd party libraries and Firebase services to add functionality to your app. It would be helpful if you go through the official documentation for each component.
Developing An App Using Java For Android
For expert level users of Java, programming for Android will not be difficult. Let us understand how one can go about developing an application using a step-by-step approach.
The user experience elements and the look of your app is defined using the activity_main.xml file in the /res/layout folder from the package. In this file, you will modify the string attributes and add views for the app. You can also add radio buttons or text fields based on the app requirement and design. By right-clicking on the element you added, you can select properties and modify them based on your layout.
Annotations In Android Studio
Android Studio supports annotations for variables, parameters, and returnvalues to help you catch bugs, such as null pointer exceptions and resourcetype conflicts. The Android SDK Manager packages the Support-Annotationslibrary in the Android Support Repository for use with Android Studio. AndroidStudio validates the configured annotations during code inspection.
For more details about Android annotations, seeImprove code inspection with annotations.
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What Is And Why Android
Let start with 2w Android is an open source mobile development platform that builds various open source projects. What does this mean to the developer world? Simply we can say access to source code platform that is running on Phone. This can help you to understand the interface control.
If anyone finding bug, he/she can also submit a patch for issue as its known to be more advance practice. Google has provided many groups of companies that can contribute to and also use their Android OS in their existing hardware devices. This shows Google OS wide support within the market venders.
What Is Android App Development: An Introduction To The World Of Android
History: The Birth of Android
Android vs iPhone debates has existed on chatrooms and forums for ages now. Despite its longevity, the first Android OS phone only hit the shelves just over 10 years ago. Since then, Android has become an unstoppable force. The reason Android OS is immensely popular with smartphone makers is because of Googles decision to make it an open-source OS. For those unfamiliar with what open-source software is, its a software thats distributed with its source code open for any modification. OSS includes a license for programmers to alter the software in any way they see fit.
Surprisingly, one of the founders of Android, Andy Rubin stated that Android was initially developed as an OS for digital cameras! Way back in 2004, Android pitched their OS as tech that would wirelessly connect cameras to computers. However, the market for digital cameras was slowing. Android then decided to make the switch and steer towards the direction of implementing its OS in smartphones. 2005 was an extremely important year for Android as thats when Google bought them. The original founders continued to work on developing the OS and decided that Linux would be the base of Android OS.
Introduction: What is Android?
The Launch of 1.0
Android Systems Architecture
Lets delve into the different sections of the Android software stack.
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Fundamentals Of Android Development
Regardless of the moving pieces of how applications get converted from source code to running code, from a programming perspective, there are some fundamentals to understand when starting out with Android development.
An Android application consists of one or more of the following four classifications:
- Activities: An application that has a visible user interface is implemented via an activity. When you select an application from the Home screen or application launcher, an activity is started.
- Services: You can use a service for any application that needs to persist for a long time, such as a network monitor or update-checking application.
- Content providers: The easiest way to think about content providers is to view them as a database server. A content providers job is to manage access to persisted data, such as the contacts on a phone. If your application is very simple, you might not necessarily create a content provider, however if you are building a larger application or one which makes data available to multiple activities and/or applications, a content provider is the proscribed means of accessing your data.
- Broadcast receivers: You can launch an Android application to process a specific element of data or respond to an event, such as receiving a text message.
Enough backgroundlets have a look at the development environment required to build an Android application.
Introduction To Java For Android Application Development
Android-based smartphones are in vogue due to the flexibility they offer for customization. Unlike Apples iOS, Google Android offers better user experience in terms of applications. The Android application development kit is an open-source Linux-based operation system, which has its own middleware and key applications. The platform for app development in Android is Java. This means that you use the Java library and code the applications in Java, C, and C++ programming language. But, the most widely used programming language for android application development is Java.
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Google Play Market Vs App Store
The interfaces of Google Play Market and App Store are similar – both have a home page with application listings, filters that help users to navigate and search for apps. The app description page has similar layouts – there’s a text description, a gallery, a block with app ratings and user reviews, and a download button that allows users to download an application.
Implementing Logic Using Java
After the front-end elements are finalized, the most important step remains implementing logic for all the activities to work well. The logic needs to be implemented in the MainActivity.java file from the src/com.example.tutorialapplication/ folder. The MainActivity.java file is the file that actually get converted into Dalvik compatible format and runs the application.
Let us consider that you created the front end to have a text field that displays Udemy Online Courses and here is the code snippet for this text display in the application.
This code snippet is for the MainActivity.java file.
In the above snippet, the R.layout.activity_main element calls the activity file. The onCreate and onCreateOptionsMenu are one of the many methods that are executed when MainActivity.java file executes.
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Why Java For Android Application Development
If you want to get started with application development, Google provides a Java API to get started and compiles your files into classes. Why did Android prefer Java for its development platform? There are multiple reasons such as Java is a commonly used language and many programmers know it, it can run on a virtual machine so no need to recompile for different phones, better security, many development tools available for Java, and Java is a known industry language with most phones compatible with it.
Though Google provides the Java API, Android does not use JVM to execute class files. Rather, it uses Dalvik Virtual Machine . The class files are compiled into Dalvik Executable format, and bundled as Android Package along with other resources.
With Java, if you are aware of object-oriented programming principles, creating applications for android will be much simpler than iOS app development.
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We will start from the ground up, progressing from simple projects to full fledged applications that are ready for the Google Play Store. In these ten weeks, learn to develop for the world’s largest mobile platform by harnessing powerful and modern tools through Kotlin to create Android applications for over 2.5 billion users.
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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 should all be run asynchronously in the background . This is why it is important to learn the Java language concurrency facilities.
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Providing Text Element In The Strings File
All the textual elements used in the UI of the app are provided in the Strings file. This includes button names, labels, default text on-screen, and so on. The following code snippet shows the default string declarations:
< resources> < string name="app_name"> Udemy Online Courses< /string> < string name="udemy_courses"> Udemy Online Courses!< /string> < string name="menu_settings"> Settings< /string> < string name="title_activity_main"> MainActivity< /string> < /resources>
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Make The Text Box Size Flexible
To create a layout that’s responsive to different screen sizes, you need to make the text boxstretch to fill all the horizontal space that remains after the button and margins are accounted for.
Before you continue, click in the toolbar and select Blueprint.
To make the text box flexible, follow these steps:
Figure 8. The result of choosing Create Horizontal Chain
Figure 9. Click to change the width to Match Constraints
Figure 10. The text box now stretches to fill the remaining space
Select both views. To do so, click one, hold Shift, then click the other, and then right-click either one and select Chains > Create Horizontal Chain. The layout then appears as shown in figure 8.
A chain is a bidirectional constraint between two or more views that allows you to lay out the chained views in unison.
Match constraints means that the width expands to meet the definition of the horizontal constraints and margins. Therefore, the text box stretches to fill the horizontal space that remains after the button and all the margins are accounted for.
Now the layout is done, as shown in figure 10.
If your layout didn’t turn out as expected, click See the final layout XML below to see what your XML should look like. Compare it to what you see in the Code tab. If your attributes appear in a different order, that’s okay.
See the final layout XML
Familiarize Yourself With The Files
I remember the first time I tried Android app development. I loaded up Android Studio and was immediately baffled by what I saw. There are just so many different files, multiple types of code, folders, and more! This was worlds away from the single blank file I was used to working with in Python or even QBasic .
This can be rather daunting, but heres what you need to know.
The file that is open is MainActivity.java or MainActivity.kt. This is the main logic file for the activity that is going to define how your app behaves. Look on the left, and youll see that this file is found in: MyApplication > app > src > main > java > com > companyname > myapplication.
The folders used are important for Android app development, as they help Android Studio and Gradle to find everything and build it correctly . Suffice to say, you cant just rename these as you please!
Youll notice that there is already some code on the main page. This is what we call boilerplate code, meaning that it is code that is almost identical across different app projects and that is needed to make basic functions work. Boilerplate code is what youll find yourself typing out over and over again! One of the benefits of Kotlin is that it requires less boilerplate, meaning that youll have less code on your screen if that is what you chose.
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Benefits To Develop For Android Platform:
- Begin Development with Zero Costing: The Development tools are free to download and as far as distribution of application is concerned, Google charges very nominal charges.
- Independency to Innovate & Team up: Android an open source platform based on Linux kernel, developers are free to contribute by building application on Android devices. Developer are not required to sign any DNA just need to collaborate and share codes with each other. Great advantage is we can reuse in your own projects to bring them to market much faster.
- Open Distribution Platform: With very little restrictionon content and functionality, it allows developers to distribute their application through other channel at free of cost.
- Multi Platform and Carrier Support: With variety of hardware devices by Android OS, Developer can perform development on different platforms like Windows, MAC OS or Lunix. A large number of telecom carriers currently offer Android powered phones.
Where To Go From Here
With these two basic concepts in mind, you have two options. If you prefer staying in the main documentation, which makes it easy to branch off to other topics to learn more about specific aspects of building an app, you can proceed to the next lesson to build your first app. However, if you like to follow step-by-step tutorials that explain every step from beginning to end, then consider the Android Basics in Kotlin course.
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Java Vs Kotlin For Android App Development
One of the biggest decisions youll need to make as an Android developer is whether youre going to learn Kotlin or Java. Both languages are officially supported by Google and Android Studio, but they have some distinct differences.
Java has been supported by Google the longest and is what developers have been using to craft Android apps for years. Java is also one of the most in-demand programming languages in the world, which makes it a great choice for those who want to begin a career in development. As the oldest Android programming language, there is also slightly more support for Java vs Kotlin, although its not by much.
Kotlin, on the other hand, has become Googles preferred choice for Android development. This is the default when starting a new app, and it is likely to become more common going forward. Kotlin is also significantly easier to get to grips with if youre a complete beginner.
For these reasons, Kotlin is probably the language of choice for Android developers that are learning for fun, or that have no aspirations to develop for other platforms. However, Java makes more sense if youre interested in becoming a professional developer.
You can learn more about the two options here by reading our guide to Kotlin vs Java for Android.
Beginners In Android Development Should Start With Java
The first and foremost thing is that Android development is not everything. As a programmer, you may be starting your career with Android development. But if you start with a well-established language like Java, you become a part of the bigger Java community and market, which directly means more job opportunities.
The second and more important thing is that there is a huge community of Java programmers, which means you can find answers when you are stuck. This is very important because, as a beginner, you will face a lot of technical problems and you might not know where to head when you are stuck.
When you search Google with a Java problem, you are bound to get answers. But the same cannot be said for Kotlin, which is still a new programming language.
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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 . To understand the basic concepts and terms of how the platform operates, you can use the Git Pocket Guide.