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[MUSIC]

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Originally in Android development,
a ListView was the only option for

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showing items in a scrolling list.

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It provided a convenient
way to display the list and

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offer some good functionality and
conveniences.

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We were able to easily add things
like on item click listeners and

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use default adapters with ListViews.

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Android 5.0,
lollipop introduced the RecyclerView.

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And through the support
library makes it compatible

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all the way back to Android API level 7.

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I've mentioned that we'll be using
a RecyclerView to display our data,

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I'm all for recycling.

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Paper, cardboard, batteries, but

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what exactly is a RecyclerView
when it comes to Android app?

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What are we gonna be recycling there?

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The RecyclerView widget is,
according to the Android documentation,

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a more advanced and
flexible version of ListView.

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In a nutshell, it is great for
large sets of data and

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certain operations like
animating items in a list.

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And as I mentioned,
it's backwards compatible.

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It allows for the reuse or
recycling of the ListItemView holder.

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When our list contains more information
than we'll want to display at one time,

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Android takes a just in time approach.

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This means that Android
creates the display for

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list items right when they
are needed on the screen.

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Now there is still some overhead in
creating views for the first time.

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So, to make this as smooth as possible,
we can create one set of views for

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just the items that can fit on the screen.

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We can then reuse those
containers over and

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over again as one item scrolls off or
reclaim the view add object for it and

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fill it with new data from the next item
that is about to scroll onto the screen.

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This saves room in memory and
offers great performance improvements

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by recycling the container as
it scrolls off the screen.

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Just the list of data is needed to
maintained and bound to the view.

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At a high level using a RecyclerView
has the following steps: first,

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we define a model class to
be used as a data source.

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We've done this already
with our hour class.

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Second, we add a RecyclerView
to our activity.

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Next, we create a custom layout for
the raw of data to be displayed.

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In our case it would be
hourly weather data,

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with the hour, an icon,
a summary and estimated temperature.

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Fourth, we need to create an adapter which
we'll talk about more later in the course.

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Finally, we need to bind our data to
our model to populate the RecyclerView.

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There are several steps to this and it can
get pretty complicated rather quickly.

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Don't worry, we'll work through
them one at a time, step by step.

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First, we'll create an hourly forecast
activity to house a RecyclerView and

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build an adapter for
it to display our data.

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We'll also need to set
up a view holder and

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use the list item layout to
handle the custom layout.

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I know it's a lot to cover, but
once you have this project completed,

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you'll have a terrific sample to build
from for your own future projects.