There is object array received from server
there are two ways to show items :
Adapt Objects To ListView
Use Scroll View
So If I use scroll View and add items programmatically, There are some Questions:
Does Adding Items Programmatically Cause Out Of Memory ?
Does It Need To Remove Items from memory ? or it will remove automatic after onDestroy Called or Items moved out of screen?
Regards
If the data set is large, a ListView won't stop OOMs by itself, you will have to avoid loading the entire data set in memory by using a CusorAdapter backed by some non-memory data store (like a sql database).
A ListView will reduce the amount of memory that the Views use to represent the data to the user, since it will only initialise Views that the user can see (and recycle Views if possible when the user scrolls).
Since only the Views visible are loaded with a ListView, performance should* also be better since the layout process will be quicker.
In most cases, a ListView would be better for this type of thing.
(*) If the adapter's getView or bindView e.t.c. are complex, or each row in the list has its own view type, the scrolling performance could actually be worse.
Listview is the Best case for you. and I will prefer to use volly library of android . It is easy to use and very handy and helpfull.
Related
I want to put a list of items I am extracting from a firebase database. I was using RecyclerView for this but now I came to know that we can create Buttons, TextViews etc programmatically. I was wondering if there are any benefits of recyclerview or any special cases where it is preferable to use recyclerview.
Use RecyclerView, it is memory efficient. It does create view when it is visible and destroys it when it is not visible anymore, this way you can have infinite list without using a lot of resources.
Not bad thing to maintain view dynamically, But you need to know full concept of recycler view before taking the decision because there are lot's of aspect depend on when you are deciding to any component
Key aspects,
- Why you are using view?
- Is it sequential?
- All the data in the list are the same type?
- Also, How many records in the list if there is only tow-three record then no need to take the recyclerview.
Ultimately recyclerview is the optimized view for list out the item as a list,
Also, we suggest if your most of the data same type then take recyclerview don't do at dynamically, Because name self saying how recycler view (Recycle) will work
What will happen if we keep on loading thousands of items in any type list in Android? Will Android be able to recycle it correctly?
Short Answer
In your case, there Would not be any problem in recycling of list view or recycler view.
Long Answer
The list view or recycler view would just load and show the amount of data which are visible on the UI. So the size of the items in it is not any problem.
BUT
there are some cases which would make problem.
for example if you put a recycler view inside a Scroll view!
In such cases all of the items are loaded and there is no GC. That's where you would have big problems with lots of data.
List is an Interface, not a class, so there are ArrayLists and LinkedLists and several other types, but ArrayLists for example can handle up to Integer.MAX_VALUE elements. I've never had a problem with an ArrayList and garbage collection at least and thousands of items is far below the limits of that class.
I'm trying to show an animation with all Views that I've created from an adapter. When I scroll down, it shows the animation correctly, but when I scroll up, I see these Views recreate themselves and show the animation again. Then, when I scroll down, it happens again.
My assumption is that the mechanism of creating a View from an adapter is to load the View into memory; just the group of Views which are on screen right now (but above and below views are not loaded into memory). These will be loaded again when I scroll to these views, right?
Is there any way to fix this problem?
PS: Sorry for my English, I hope you understand my problem.
My assumption is that the mechanism of creating a View from an adapter
is to load the View into memory; just the group of Views which are on
screen right now (but above and below views are not loaded into
memory)
That's somewhat correct: a ListView will not try to visualize any data that isn't (at least partially) visible. It also 'recycles' views, meaning that any view that isn't currently used to present data to the user and is of the same 'type' as the next data item, may get reused.
Hence you shouldn't rely on persisting data with or make any assumptions about the existence of particular views. In stead, use something that's separate from the views; e.g. the dataset you're visualizing.
Quite often, you'll supply a list of POJOs to a BaseAdapter or ArrayAdapter. You could simply add a boolean to the POJO indicating whether it should animate or not, and change that whenever the animation for that particular item finishes. Alternatively, you could keep track of these values in a separate collection (which is probably the more straightforward approach if you're dealing with a Cursor as data source rather than POJOs).
What is the best way of constructing a ListView that uses the least memory possible? This is important, because I met a few implementations and most of them is lagging when I scroll the ListView on low-end devices, but I saw a few apps, where the scroll is very smooth, even on low-end devices. How can it be done? What is the most efficient way from a memory usage point of view to construct such a ListView?
recycle your views in getView()
use ViewHolder pattern
use lazy loading if you have a lot of data to fill the list with
use Cursor as underlying data instead of object list built from cursor if your data comes from database, you save memory by not creating additional objects.
see http://www.google.com/events/io/2010/sessions/world-of-listview-android.html
see http://android.amberfog.com/?p=296
You will have to use the ViewHolder pattern.
Look at this code with description to increase the efficiency of lisview.
Keep in mind when you have lots of data to show in listview then at a time do not load all data . First load 2o data then load another when listview reaches at end.
This is also another way to increase the efficiency of listview.
Is there a way to call BaseAdapter.notifyDataSetChanged() on a single element in the adapter.
What I am trying to do is update the data and reflect those changes in the containing ListView. The problem is that sometimes the change is so small that it seems ridiculous that I have to refresh the whole view rather than the single item in the view that has been updated.
I am not aware of such method. If it's really important, you can always find individual item view to update. But I don't think that it worth it as Android is pretty efficient in updating list views. So it will not do much extra work (definitelly not going beyond items currently visible on the screen).