recyclerview, beyond the basics - commonsware · not part of recyclerview itself must implement...

Copyright © 2015 CommonsWare, LLC

RecyclerView, Beyond the

Basics

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What You Should Already Know

● Creating a Basic RecyclerView● LinearLayoutManager, custom adapter and view

holder

● Showing Dividers● Handling Clicks

● Including ripple effects on Android 5.0+

● Other Types of Layout Managers

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Models and Their Collections

● No Stock RecyclerView Adapters by Collection Type● E.g., ArrayAdapter, CursorAdapter

● Any Collection Will Work● You just need to be able to do the positioning and

stuff● Example: cursors

– Database queries– Content provider queries

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Models and Their Collections

● Warning: Beware Stateful Collections!● Example: cursors and positions● Problem: many view holders will be using the same

collection● Solution: do not have view holders hold the

collection, but simply bind the data in onBindViewHolder() directly

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Multiple View Types

● Scenarios● List with headers● Different views for different types of models in

heterogenous list● Staggered grid with “hero element”

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Multiple View Types

● Implementation● Dedicated view holder per view type

– Perhaps an interface for common operations, like binding

● getItemViewType()– Works akin to ListAdapter equivalent

● onCreateViewHolder()– Gets view type passed in as parameter, for if/switch

to instantiate the proper view holder

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Choice Modes

● Not Part of RecyclerView Itself● Must implement yourself

● Major UI Approaches● The CompoundButton

– CheckBox for multiple-choice– RadioButton for single-choice

● The activated state

● Optional: Action Mode Support● Again, not part of RecyclerView

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Changing the Contents

● Automatic Changes via SortedList● Implement a SortedList.Callback to find out about

each shift in the SortedList contents based on add/insert/remove operations

● Pass that information along to adapter

● Manual Changes● notifyItemInserted(), notifyItemRemoved(), etc.

● Animated Effects