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Adapting the Adapter
4:48With a ViewHolder in place, the rest of the Adapter Class can be completed.
With our view holder configured and
leveraging the power of the Android data
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binding library, we need to turn our
attention to the rest of the adapter.
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Recall that this view holder allows for
smooth scrolling in our recycler view.
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We'll fill in the adapter so
that it can convert an object
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at a given position in our
dataset to a list row item.
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We saw that our adapter requires
three different methods.
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onCreateViewHolder(), which is called
right when the adapter is created, and
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is used to initialize the ViewHolder.
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onBindViewHolder(), which is called for
each ViewHolder to bind it to the adapter.
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This is where data is
passed to the ViewHolder.
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And getItemCount(),
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which simply returns the size of
the collection the items to display.
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It is used by the layout manager.
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We also need to resolve those errors.
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That's a bit of work to get done, but if
we take it step by step, we can do this.
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So let's get started.
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To start with,
we need some variables defined.
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Let's give some space.
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We need a private List<Hour> hours.
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Do the quick fix to get our imports.
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And we need our context.
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Context context.
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And we'll generate a constructor here for
our hourly adapter.
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Code > Generate > Constructor.
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Select both variables, and hit OK.
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We'll be using that over in
the activity here in a little while.
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In onCreateViewHolder(),
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we want to bind our data to the view
holder when it's first created.
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Let's update the return type from
a RecyclerView.ViewHolder to
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our hourly adapter view holder.
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Go here.
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We're gonna change that to HourlyAdapter.
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Let's scroll up here to
give us some working room.
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Inside the onCreateViewHolder method,
we create our binding.
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So HourlyListItemBinding.
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We will call it binding.
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DataBindingUtil.
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So we can chain on our inflate method
here, just like we do in main activity,
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and use the layout inflater.
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Let's drop this down to a new line.
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We'll inflate.
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Layout inflater.
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We want parent.
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And getContext.
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The next parameter here is our layout.
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We drop that down.
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R.layout.
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It's the hourly_list_item.
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And use the quick fix to import R.
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And our ViewGroup is parent And we don't
want this attached to to the parent,
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so we can pass in false
Let's clean this up here.
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Drop this down to a new line.
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Recall that inflating in this manner
inflates the binding layout and
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returns the newly created binding for
that layout.
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Now, we just need to return our view
holder and pass in the binding.
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so we will return a new ViewHolder(),
and pass in our binding.
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Okay, onto onBindViewHolder,
where we aren't passing
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any recyclerView.ViewHolder,
just a ViewHolder.
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So we can delete that.
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Inside onBindViewHolder,
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we need to find which list item in
our hourly data we're working with.
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So Hour hour = hours.get(position).
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And we bind that to our ViewHolder.
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So there's our view holder.
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hourlyListItemBinding.setHour(hour).
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And that's it for that method.
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And then, getItemCount, we just need
to return the size of our data.
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So we can return hours.size().
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We should be all set with our adapter and
ViewHolder.
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Next up, we'll head into our
hourly forecast activity, and
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connect the pieces together in there.
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