A better way to display collections in Android
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last updated: 2018-01
RecyclerView is a view group for displaying collections; it is designed to be a more flexible replacement for older view groups such as ListView and GridView. This guide explains how to use and customize RecyclerView in Xamarin.Android applications.
Many apps need to display collections of the same type (such as
messages, contacts, images, or songs); often, this collection is too
large to fit on the screen, so the collection is presented in a small
window that can smoothly scroll through all items in the collection.
RecyclerView is an Android widget that displays a collection of
items in a list or a grid, enabling the user to scroll through the
collection. The following is a screenshot of an example app that uses
RecyclerView to display email inbox contents in a vertical
RecyclerView offers two compelling features:
It has a flexible architecture that lets you modify its behavior by plugging in your preferred components.
It is efficient with large collections because it reuses item views and requires the use of view holders to cache view references.
This guide explains how to use
RecyclerView in Xamarin.Android
applications; it explains how to add the
RecyclerView package to
your Xamarin.Android project, and it describes how
functions in a typical application. Real code examples are provided to
show you how to integrate
RecyclerView into your application, how
to implement item-view click, and how to refresh
its underlying data changes. This guide assumes that you are familiar
with Xamarin.Android development.
RecyclerView is often associated with Android 5.0
Lollipop, it is offered as a support library –
works with apps that target API level 7 (Android 2.1) and later. The
following is required to use
RecyclerView in Xamarin-based
Xamarin.Android – Xamarin.Android 4.20 or later must be installed and configured with either Visual Studio or Visual Studio for Mac.
Your app project must include the Xamarin.Android.Support.v7.RecyclerView package. For more information about installing NuGet packages, see Walkthrough: Including a NuGet in your project.
RecyclerView can be thought of as a replacement for the
GridView widgets in Android. Like its
RecyclerView is designed to display a large data set
in a small window, but
RecyclerView offers more layout options and
is better optimized for displaying large collections. If you are
ListView, there are several important differences
RecyclerViewis slightly more complex to use: you have to write more code to use
RecyclerViewdoes not provide a predefined adapter; you must implement the adapter code that accesses your data source. However, Android includes several predefined adapters that work with
RecyclerViewdoes not offer an item-click event when a user taps an item; instead, item-click events are handled by helper classes. By contrast,
ListViewoffers an item-click event.
RecyclerViewenhances performance by recycling views and by enforcing the view-holder pattern, which eliminates unnecessary layout resource lookups. Use of the view-holder pattern is optional in
RecyclerViewis based on a modular design that makes it easier to customize. For example, you can plug in a different layout policy without significant code changes to your app. By contrast,
ListViewis relatively monolithic in structure.
RecyclerViewincludes built-in animations for item add and remove.
ListViewanimations require some additional effort on the part of the app developer.
This topic explains how the
ViewHolder work together as helper classes to support
It provides a high-level overview of each of these helper classes and
explains how you use them in your app.
This topic builds on the information provided in
RecyclerView Parts and Functionality
by providing real code examples of how the various
RecyclerView elements are
implemented to build a real-world photo-browsing app.
This topic adds additional code to the example app presented in
A Basic RecyclerView Example
to demonstrate how to handle item-click events and update
RecyclerView when the
underlying data source changes.
This guide introduced the Android
RecyclerView widget; it explained
how to add the
RecyclerView support library to Xamarin.Android
RecyclerView recycles views, how it enforces the
view-holder pattern for efficiency, and how the various helper classes
that make up
RecyclerView collaborate to display collections. It
provided example code to demonstrate how
RecyclerView is integrated
into an application, it explained how to tailor
layout policy by plugging in different layout managers, and it
described how to handle item click events and notify
of data source changes.
For more information about
RecyclerView, see the
RecyclerView class reference.