Fragments Walkthrough

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Android 3.0 introduced Fragments. Fragments are self-contained, modular components that are used to help address the complexity of writing applications that may run on screens of different sizes. This article walks through how to use fragments to develop Xamarin.Android applications, and how to support fragments on pre-Android 3.0 devices.

Contents

Overview

Part 1 - Walkthrough

Part 2 - Supporting Pre-Honeycomb Android Using Support Packages

Summary

Overview

In this article, we’ll walk through how to create an application that will display a list of Shakespeare’s plays and a quote from each selected play. Our app will utilize fragments so that we can define our UI components in one place, but then use them on different form factors. For example, the following screen shots show the application running on a 10” tablet, as well as on a phone:

 

This walkthrough will cover the following topics:

Creating Fragments – shows how to create a fragment to display a list of Shakespeare’s plays, and another fragment to display a quote from each play.

Supporting different screen sizes – shows how to layout the application to take advantage of larger screen sizes.

Using the Android Support Package – implements the Android Support Package, then makes some minor changes to the Activities in the application, allowing it to run on older versions of Android.

Requirements

This walkthrough requires Xamarin.Android 4.0 or higher. It will also be necessary to install the Android Support Package, as outlined in the Fragments documentation.

Introduction

In the example we’ll build in this walkthrough, the Activities do not contain logic for loading the list, responding to user selection, or displaying the quote for the selected play. This logic exists in the individual fragments. By placing this logic in the fragments themselves, we can break up the workflow of the application to support large screens with one Activity or small screens with multiple Activities without having to write different logic for each Activity. On a tablet, both fragments will be in one Activity. On a phone, the fragments will be hosted in different Activities.

This application includes the following parts:

MainActivity – displays one or both of the fragments, depending on the size of the screen. This is the startup Activity.

TitlesFragment – displays a list of Shakespeare’s plays from which the user may select.

DetailsFragment – displays the quote from the selected play.

DetailsActivity – hosts and displays the DetailsFragment. This Activity is used by devices with small screens, such as phones.

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