Book Image

Android Programming for Beginners

By : John Horton, Paresh Mayani
Book Image

Android Programming for Beginners

By: John Horton, Paresh Mayani

Overview of this book

Android is the most popular OS in the world. There are millions of devices accessing tens of thousands of applications. It is many people's entry point into the world of technology; it is an operating system for everyone. Despite this, the entry-fee to actually make Android applications is usually a computer science degree, or five years’ worth of Java experience. Android Programming for Beginners will be your companion to create Android applications from scratch—whether you’re looking to start your programming career, make an application for work, be reintroduced to mobile development, or are just looking to program for fun. We will introduce you to all the fundamental concepts of programming in an Android context, from the Java basics to working with the Android API. All examples are created from within Android Studio, the official Android development environment that helps supercharge your application development process. After this crash-course, we’ll dive deeper into Android programming and you’ll learn how to create applications with a professional-standard UI through fragments, make location-aware apps with Google Maps integration, and store your user’s data with SQLite. In addition, you’ll see how to make your apps multilingual, capture images from a device’s camera, and work with graphics, sound, and animations too. By the end of this book, you’ll be ready to start building your own custom applications in Android and Java.
Table of Contents (37 chapters)
Android Programming for Beginners
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

ListView and BaseAdapter


In Chapter 5, Real-World Layouts, we used ScrollView and we populated it with around 20 TextView widgets, so we could see it scrolling. We could take what we just learned about arrays and ArrayList and create an array of TextViews and use them to populate ScrollView. This sounds like a perfect solution to display excerpts of a note in our Note To Self app.

We could create TextViews dynamically in Java code, set their text property to be the title of a note, and then add TextViews to LinearLayout that is contained in ScrollView. However, this is imperfect.

The problem with displaying lots of widgets

This might seem fine, but what if there were dozens, hundreds, or even thousands of notes? We couldn't have thousands of TextViews in memory because the Android device might simply run out of memory or, at the very least, grind to a halt as it tries to handle the scrolling of such a vast amount of data.

Now consider that we want each note in ScrollView to show an image about...