Book Image

Android Application Development Cookbook - Second Edition

By : Kyle Mew
Book Image

Android Application Development Cookbook - Second Edition

By: Kyle Mew

Overview of this book

The Android OS has the largest installation base of any operating system in the world; there has never been a better time to learn Android development to write your own applications, or to make your own contributions to the open source community! This “cookbook” will make it easy for you to jump to a topic of interest and get what you need to implement the feature in your own application. If you are new to Android and learn best by “doing,” then this book will provide many topics of interest. Starting with the basics of Android development, we move on to more advanced concepts, and we’ll guide you through common tasks developers struggle to solve. The first few chapters cover the basics including Activities, Layouts, Widgets, and the Menu. From there, we cover fragments and data storage (including SQLite), device sensors, the camera, and GPS. Then we move on more advanced topics such as graphics and animation (including OpenGL), multi-threading with AsyncTask, and Internet functionality with Volley. We’ll also demonstrate Google Maps and Google Cloud Messaging (also known as Push Notifications) using the Google API Library. Finally, we’ll take a look at several online services designed especially for Android development. Take your application big-time with full Internet web services without having to become a server admin by leveraging the power of Backend as a Service (BaaS) providers.
Table of Contents (23 chapters)
Android Application Development Cookbook Second Edition
Credits
Disclaimer
About the Authors
About the Reviewer
www.PacktPub.com
Preface
Index

Creating a widget at runtime


As mentioned before, generally, the UI is declared in XML files and then modified during runtime through the Java code. It is possible to create the UI completely in Java code, though for a complex layout, it would generally not be considered best practice.

The GridView example from the previous chapter was created in code. But unlike the GridView recipe, in this recipe, we are going to add a view to the existing layout defined in activity_main.xml.

Getting ready

Create a new project in Android Studio and call it RuntimeWidget. Select the Empty Activity option when prompted for the Activity type.

How to do it...

We will start by adding an ID attribute to the existing layout so we can access the layout in code. Once we have a reference to the layout in code, we can add new views to the existing layout. Here are the steps:

  1. Open the res/layout/activity_main.xml and add an ID attribute to the main RelativeLayout, as follows:

    android:id="@+id/layout"
  2. Completely remove the...