This is not a design question, I have the item designed. I am confused on how to pull it off.
I am tasked with designing a view for Android that has a view of a user's post and the comments under it. The post contains some extra information and widely different design from the comments, but all of them need to scroll in tandem, like a web page would (Oh, how I am spoiled by my years of web dev...).
My current solution is to nest a LinearLayout (at the top of the view to contain the user's post) and a RecyclerView (below the post to display the comments) inside a vertical ScrollView. The information is actually displayed, but the RecyclerView, of course, scrolls independently of the LinearLayout above it and ruins the functionality of the view.
I wish, if possible, to keep the RecyclerView in use
The best case scenario would be to have the LinearLayout with the post scroll a certain amount, and then the RecyclerView take over. However, I don't want to poison my codebase with 200+ ugly lines of code to achieve this, so if this is a laborious task to complete, I would rather look for alternatives.
The first thing to understand is: do you really need a RecyclerView, or even better, do you really need recycling?
If the answer is yes, the way to go is two different item types in the RecyclerView's Adapter (for more details, see here or here). This concept was already present in the ListView: the main difference is that RecyclerView enforce the use of the View Holder pattern. It is not so complex, and, more importantly, is the way the RecyclerView is supposed to solve that problem. Depending on your UI design, you may also want to have different view types for different types of comments (plain text, images, ...). Remember that, when the RecyclerView is included in a ScrollView, the recycling won't work, because all the items in it will be drawn at once to compute the height of the content of the parent ScrollView.
If the answer is no, then you could just create your views at runtime and add them to a parent LinearLayout in a ScrollView. It is really nothing more than a for loop.
A more fancy approach would be to use an ItemDecoration for the user's post, but I don't see any specific advantage in this case.
Related
I'm a flutter user trying out kotlin dev first time, but im kinda confused what the best alternatives for this type of layouts are.
I understand that I use recyclerview for a dynamic number of items. And since theres two dynamic ones (one for number of sets, one for each exercise). Do I use two nested recyclerviews?
It really depends what you're doing here. A RecyclerView is basically a list, so it's a good choice for a scrollable set of items - which it looks like your Exercises are. But how do you want to display those weights?
It's possible to make them scrollable, so some of them aren't visible on the screen (the categories on the Play Store act like this). For that you would need a nested scrolling view of some kind - could be a horizontal RecyclerView, or it could just be a ScrollView wrapped around a LinearLayout you throw views into.
But the other option you might want, is that for each Exercise, all of its weights are visible in a grid of some kind. No scrolling, all there up-front to see and poke at. So the first question is which of those do you want?
I'd assume it's this version - where you can easily visualise the contents - in which case you're not talking about nested lists, it's just one list, and each item contains a grid you can add things too. For that setup, there's GridLayout, TableLayout, and ConstraintLayout Flow (which acts like FlexBox if you're familiar with that). So in the layout for an item in your list, you have a container for stuff, and you put the stuff in it, and the container expands vertically as needed
I am trying to achive this:
First I tried by putting all my recyclerviews (with WRAP_CONTENT) inside a nestedscrollview. That worked, but the performance was awful. Then I tried to set a height for my recyclerviews, that was a lot better (especially the first gridlayout and the horizontal linearlayout loaded very fast), but still had the problem with the dynamic "category" part.
Now I am trying to put all my recyclerviews inside a single recyclerview with different viewtypes. Since that is a pretty big deal (I need to refactor a lot of code because I have diveded every area from the screenshot inside a single fragment and now I need to put all that code inside an adapter) I wanted to ask if I can actually expect any gain from this, because in the end its again a "nestedscrollview" (made by myself, but...). Or if there is some other "best practice" way to achive this layout.
Thank you
Edit:
As expected this didnt do the trick neither. When just the two first recyclerviews are added as viewtype it scrolls and loads smoothly. But as as soon as I try to add the category items (below the category), I notice a lag and especially when selecting multiple categories and scrolling fast up, there is noticable lag. I guess I will have to change my layout and move the category selection part inside a separate view, just need to come up with a user friendly solution. But its acutally quite dissapointing that, in my opinion such trivial task, laying out multiple tables, is such a pain in the ass on android.
I didn't manage to get it working with standard android stuff.
Now I am using epoxy from airbnb ,and I have converted all my views from nestedscrollview to the epoxy recyclerview. Its a great library, and airbnb use it too for all their views.
Nevertheless it's sad that the android dev team doesn't address this problem and provide a solution besides the info "don't nest multiple scrollviews(recyclerviews) that scroll into the same direction".
You can use Recyclerview in recyclerview.
https://irpdevelop.wordpress.com/2016/02/10/horizontal-recyclerview-inside-a-vertical-recyclerview/
And make sure to use multiple view types.
I am trying to achieve a gridview with a different number of items in each row, depending on the width of each item. I want it to look like the one on the Medium app, as shown below:
How can i achieve this?
You can approach the problem in two main ways:
Use ScrollView with a Linear- or RelativeLayout inside. Then you would add the items in your code, measuring each and putting them into new rows when required. This will require some logic to be created, but is achievable. The ScrollView will take care of the scrolling in case the contents exceed the screen height. The problem with this solution is that you will not have a recycling mechanism, which can lead to problems with memory when the list gets long.
Use RecyclerView! :-D One of the awesome features of the RecyclerView is the fact that while providing the standard Adapter-based concept of the list of items, it also allows you to implement a custom LayoutManager. Create your own implementation of LayoutManager which positions the items based on their measured with and you are done, the RecyclerView will take care of scrolling and recycling the items for you! :-D This will take some getting used to, especially if you have no experience with RecyclerView, but the whole thing should take no more than several hours and is, in my humble opinion, really worth it.
You are free to choose either, but the second approach is more modern and, in general, easier to implement. In general, you should learn to use the RecyclerView, it helps a lot and is quicker to implement than the good old List- and GridViews, once you get the hang of it.
I'm making sort of a news feed, that is displayed below a static menu. To avoid the news feed from being scrolled in the tiny bit of space that's left after the menu, I wanted to scroll both the menu and the newsfeed at the same time.
Now I'm realizing this with a LinearLayout, so it doesn't scroll itself like the listview. But my question is, is using a LinearLayout, which from what I know doesn't reuse views like a listView, bad practice? How likely am I to get into memory issues, since the news feed can have A LOT of views, and they all contain images.
Many thanks!
Apparently there is a pretty good chance for you to get an OutOfmemmoryexception in no time with this approach,If you want to go with re-using the views
I suggest you should go with the new RecyclerViews in Android,
Go here for a tutorial on recycler views
I don't know if this qualifies to be an answer. But if you are using a LinearLayout with a header view and a ListView inside it, then there are no issues. Since the main worry you have is the news feed which would be recycled by the ListView. Neglecting to use view recycling is asking for trouble, and will likely break after 50 or so (Android hates images).
As for the header that must disappear. I would avoid putting it as the first item in a ListView as suggested in the comments, and rather have it static in the LinearLayout. And use a view translation and/or transparency to hide it. This keeps the option availible to display the header at any point, regardless of the list's scroll.
Do we get any benefits of implementing a ListView for which every item would have different layout? Would it be a better idea to put those items into ScrollView with LinearLayout instead?
Intuitively, it seems like using a ListView may still give better performance, though it might be negligible depending on the size of your content. Because the ListView inflates the views as it needs them, it seems like you might save some time by not parsing/rendering views that a user might never see. A long ScrollView with a bunch of views inside seems like it would take additional time when first launched, since the view hierarchy is more complex.
I do think Michael is mostly correct though, that the main advantage of a ListView is that views are reused, which saves on memory/processing. Unless you have a ton of content in the ScrollView, I suspect the performance difference is not significant, and will almost definitely be more complex -- in particular, having to create an adapter that knows how to create each view type for each row.
I don't understand why you may use ListView for this. Listview is a list of common data using the same layout if you click on it. Users depend on same/similar GUI patterns.
How about Sliding Tabs or the newer navigation drawer, link NavigationDrawer.
If you like sliding tabs, then I can give you more details.