So basically here is the setup I want and this is what I have. I currently have 2 adapters merged into 1 mergeAdapter to get the functionality of stories being the "header" of the app. Now the problem is they are all together inside a recycleview that's vertical. I need the first adapter to be inside the mergeAdapter but have a horizontal layout. I've asked around and it seems that I have to inflate the recycle view inside my header adapter and then use that as the layout, but I have no clear idea how to achieve this.
This is the response that I got:
"Technically it really is in theory "as simple as" inflating a layout that contains a RecyclerView as an item, and setting it up as an item view type. and getting the list to show into that item.
You really just need to create 2 adapters (if you go the MergeAdapter route), where one displays 1 item of a horizontal recycler view, and the other displays n items of the vertical list. Then put the two adapters in a MergeAdapter, now you don't even need to worry about item view types. That's what's thrown people off for almost a decade."
Edit:
To clarify, I have no idea how can adapters inflate anything other than view holders. And how can I inflate a recycle view and then use attach views to it, where do I even create it, how do I hold a reference to it in the adapter? I understand the concept behind it but I couldn't' find any examples that utilize this online so I've had no luck. Basically, if anyone can just describe the thought process behind it but a little bit more concrete, I cannot wrap my head around it atm.
Eg. You'd inflate the recycle view with inflater.inflate(R.id.recycleview) inside the init of the adapter and then store it in a variable to use in bindviewholder...
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Android Recyclerview vs ListView with Viewholder
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I was reading about the difference b/w recyclerview and listview and found out that recyclerview is faster than listview.
I tried to search online but not found any satisfactory answer I know it is used ViewHolder pattern and Notifying adapter but what does it does intearlly so it is faster?
Recycler View you could say is an efficient way to create list of views.
If you have 1000 items like ur contact list , and If ur visible screen can show only 10 items at once, it will Create only 10+1 (or +2) Views and as u scroll , items/views that left will be reused (not create) to show new data.
Recycler View by default does this, where as List View by default doesn't do.
There are some differences between these two views.
ListView is a bit heavy and it has a lot of responsibilities. Whenever we have to handle the list, such as to configure it in some way, the only way to do this is through the ListView object or inside the adapter.
A lot of bad things in the ListView were fixed or changed in the RecyclerView. It’s more efficient by default, the layout is separated and we have more possibilities over the data set inside the adapter.
These are some crucial differences between ListView and RecyclerView:
1 ViewHolder
The ViewHolder pattern allows us to make our list scrolling act smoothly. It stores list row views references and, thanks to this, calling the findViewById() method only occurs a couple of times, rather than for the entire dataset and on each bind view.
The RecyclerView’s adapter forces us to use the ViewHolder pattern. The creating part (inflating the layout and finding views) and updating the views is split into two methods — onCreateViewHolder() and onBindViewHolder().
The ListView, on the other hand, doesn’t give us that kind of protection by default, so without implementing the ViewHolder pattern inside the getView() method, we’ll end with inefficient scrolling in our list.
2 LayoutManager
The LayoutManager takes responsibility for layouting row views. Thanks to this, RecyclerView doesn’t have to think about how to position the row view. This class gives us the opportunity to choose the way that we want to show the row views and how to scroll the list. For example, if we want to scroll our list vertically or horizontally, we can choose LinearLayoutManager. For grids, it is more suitable to choose the GridLayoutManager.
Previously, with the use of the ListView, we were only able to create a vertical-scrolling list, so it wasn’t that flexible. If we wanted grids on our list, we had to choose the other widget for that — GridView.
3 ItemDecoration
A duty of the ItemDecoration is simple in theory – add some decorations for the list row views – but in practice, it’s that simple to implement if we want to create a custom one. In this case, we should extend the ItemDecoration class and implement our solution. For example, the RecyclerView list has no dividers between rows by default and it’s consistent with the Material Design guidelines. However, if we want to add a divider for some reason, we can use DividerItemDecoration and add it to the RecyclerView. In case we use the ListView, we have to figure out rows decorations by ourselves. There is no helper class like ItemDecoration for this widget.
4 ItemAnimator
The last but not least component of RecyclerView that I want to mention is ItemAnimator. As we can expect, it’s handling row views animations like list appearance and disappearance, adding or removing particular views and so on. By default, RecyclerView’s list animations are nice and smooth. Of course, we can change that by creating our own ItemAnimator, which is also not that easy. To make it easier, we should extend the SimpleItemAnimator class and implement the methods that we need (just add animations to a ViewHolder’s views). To be honest, implementing animations on the ListView was a pain. Again, we had to figure out how we want to handle them.
5 Notifying adapter
We have a couple of cool notifiers on the RecyclerView’s adapter. We are still able to use notifyDataSetChanged() but there are also ones for particular list elements, like notifyItemInserted(), notifyItemRemoved() or even notifyItemChanged() and more. We should use the most appropriate ones for what is actually happening, so the proper animations will fire correctly.
Using ListView, we were able to use just notifyDataSetChanged() on the adapter and then had to handle the rest ourselves, again.
Because of ViewHolder Pattern.
Thats was the simplest answer. Now for some details.
What recycler view does is what it's name indicates "Recycle", yes it recycles items, and it does it with the help of ViewHolder Pattern.
By Using ViewHolder we do-not need to call findViewByID() every time we go through getView()method. The reference for all rows are stored in-memory. This increases the performance significantly, as findViewByID()is a heavy process.
Hope this clears your confusion.
My problem is simple: I need to make a layout similar to android.R.layout.simple_expandable_list_item_1 which can fit more than one textview in the layout, as well as show the little '>' symbol that indicates that the tab is expandable.
How can this best be accomplished? My first thought was to use the layout as a background of a linear layout with two textviews in it, but I can't seem to make that work.
Vogella has a pretty good tutorial on how to achieve custom list views through Adapters.
Basically, what you do is you create a Layout with the looks you want for the list items and then you extend an adapter (ArrayAdapter for instance), see section 4. Then, in your activity, you create an instance of your Adapter implementation and populate it from an Array containing the data for the list.
Also have a look at the Developers site for how to make the list scroll smoothly with the ViewHolder pattern.
And if you feel you need more info on the expandable part maybe the hive can help.
I have one question for list view. At the time of creating list item in getView() method, which is a good option for list view. Creating views through coding or inflating view through xml. I am thinking about memory utilization & performance of list view.
Normally list item contain one product image with their name & 3 line description. Means one Image View & two text view.
Creating Views through code is usually not recommended and is justified only in cases when you can't deal without it. Using XML is always best practice so you should use this approach no matter where you're using your Views. Hope this helps.
You need to recycle views. Are you using a VieHolder?. My suggestion is use a view holder inflate using xml. ViewHolder will increase performance of ListView.
http://www.youtube.com/watch?v=wDBM6wVEO70. Check this link.
I have a RelativeLayout with different elements. I was planning to have two ListViews on it, but I have noticed there are some problems with scrolling. Since each ListView only shows a maximum of 5 rows should I try to make some kind of custom adapter to merge those ListViews? Or is it better to replace the ListView with a LinearLayout/RelativeLayout and add the rows as I get them manually? (like the first answer in here: android listview display all available items without scroll with static header ).
Which should be the proper way on doing this? or is there another way? Also, each row will have an OnClickListener.
There's two solutions if you'd like to keep your list... list-y, without having to prerender all the row Views like the above solution suggests (which can be slow to render, eats RAM and doesn't scale nicely to more than a screen or two of Views, but is a fine quick solution for smaller lists, though I'd just use a bunch of Views in a LinearLayout in a ScrollView rather than a ListView in that case).
Write a custom ListAdapter, overriding getItemViewType, getViewTypeCount and GetView to inflate the proper kind of view and recycle appropriately for your two types of views. You'll also either need to override getItem to contain custom logic for figuring out which set of source data to look in and to map the data accordingly, or mush the data down into one list of Objects (if you're using an arrayadapter) and cast in the getView method (probably a bit slower than handling it in the getItem without casting).
Just use cwac-merge, a view-and-adapter wrapping adapter. You can put two ListAdapters into a MergeAdapter and set that as your single ListView's adapter.
I had problems with scrolling. I never figured out how to have the ListView share vertical space with a different View, and have a single scrollbar for them both.
I worked around it by having everything that needs to scroll on the layout a row in the ListView.
Adding views as rows to a LinearLayout may have problems scaling up, but I think you'll be OK if you only have 10 rows in total. On 1st gen Android devices it'll probably start to get sluggish around 20 items (depends on Layout complexity obviously). ListView scales up by only inflating views as they come on screen.
So in answer to your question either of the two alternatives you suggest will be OK, but the LinearLayout option will be the easiest to code.
I want to generate a ListView that has some dividers between some of the entries, like it can be seen in some of the property sections. See the example below. I try to generate a List that consists of some textviews followed by one of the fancy dividers explaining the next part of the list and then again some text views. How can this be done? I thought about creating different views to add to the list? Is this the way to go?
I got a solution. I don't know if it is the best one.
I use a custom adapter derived from ArrayAdapter for the list as described in this tutorial. In the adapter class I check if the position in the getView method is a normal row, then I inflate the row layout. If it is the first row from a new group I inflate a headline layout that is a normal row plus the group headline above it.
If you don't want to mix the header into one of your rows. Consider the following solution:
You can overwrite the two methods getItemViewType and getViewTypeCount.
You now have a list that can display different rows. You need to check the expected view type for the item in the getView Method and inflate different layouts depending on it.
The list will handle the recycling for you in a way that it will return only correct recycle views to your getView method, this means if the recycleView is not null it can be used to display your current cell.
You can use my SectionedAdapter, if GPLv3 is acceptable (licensed that way due to some upstream code). You can use my MergeAdapter, if you need something more flexible and with a less-limiting license (Apache 2).
I think you might be looking for android.widget.ExpandableListView
http://developer.android.com/reference/android/widget/ExpandableListView.html
I'm also interested in an answer to this. There must be a more straightforward way to do this.
In looking at the Adapter, there's a method, Adapter.getItemViewType(int position).
ListView defines a return value, ITEM_VIEW_TYPE_HEADER_OR_FOOTER which indicates if the returned item is a header or footer.
I haven't tried it, but I assume if you create your own Adapter and return an item with the type indicating it is a header or footer, that the ListView will display it appropriately.