Book Image

Android Programming for Beginners - Second Edition

By : John Horton
Book Image

Android Programming for Beginners - Second Edition

By: John Horton

Overview of this book

Are you trying to start a career in programming, but haven't found the right way in? Do you have a great idea for an app, but don't know how to make it a reality? Or maybe you're just frustrated that in order to learn Android, you must know Java. If so, then this book is for you. This new and expanded second edition of Android Programming for Beginners will be your companion to create Android Pie applications from scratch. We will introduce you to all the fundamental concepts of programming in an Android context, from the basics of Java to working with the Android API. All examples use the up-to-date API classes, and 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 and store your user's data with SQLite. In addition, you'll see how to make your apps multilingual, draw to the screen with a finger, 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 (35 chapters)
Android Programming for Beginners - Second Edition
Contributors
Preface
Other Books You May Enjoy
Index

Creating UI widgets from pure Java without XML


We can also create widgets from Java objects that are not a reference to an object in our layout. We can declare, instantiate, and set a widget's attributes, all in code, like this:

Button myButton = new Button();

The preceding code creates a new Button by using new(). The only warning is that the Button has to be part of a layout before it can be shown. So, we could either get a reference to a layout element from our XML layout or create a new one, in code.

If we assume that we have a LinearLayout in our XML with an id property equal to linearLayout1, we could incorporate our Button from the earlier line of code in it, as follows:

// Get a reference to the LinearLayout
LinearLayout linearLayout = (LinearLayout)
   findViewById(R.id.linearLayout);

// Add our Button to it
linearLayout.addView(myButton);

We could even create an entire layout in pure Java code by first creating a new layout and then all the widgets we want to add, and finally calling...