I'm working on an android application and I have run into a decision that I can't decide on one way or another. I was hoping someone could shed some light on the common practices and any theory to back them.
Here's the issue:
I want to have a list of items with images and text like table...
Country -.-.-.-.-.-.- Pop -.- SqrMi
[img] US -.-.-.-.-.-.- xxx -.-.- xxxxx
Now the debate I'm having is whether or not to use a listview to display the data or instead nest a layout that is scrollable and just display the data that way.
Why would I even consider a nested layout? Flexibility. I can design the dividers, possibly throw in a couple graphs above/below the list. Vary the height of each of the list items (like what if I want to show a graph in one list item and no graph in the next), etc.
I'm not sure if I'm breaking the generally accepted methods here. Can anyone shed some light on this?
The only major problem you will have when using nested layouts is memory consumption. ListView reuses its children so it doesn't create more children then it can display at a single moment. This description is a little simplified but I hope it shows the purpose of the ListView. Also ListView implements its own fast scrolling so it doesn't have to measure all its children to determine its size. And ListViews use adapters to populate themselves with data. It's a nice and convenient way to obtain data.
On the other hand if you create a ScrollView with a lot of views inside it'll be slow, difficult to populate with data and it'll require a lot of memory to create all of the child views even if you don't ever see some of them.
And about flexibility of the ListView. You can store different types of view in a single ListView and you'll be able to vary the height of each of this views.
All the things you have described for your "nested layout" is achievable with ListView. Just use different types of rows, use headers/footers in adapter.
And as already Pixie said, ListView is much more memory efficient and faster.
Related
I need to create the layout as shown below. What would an optimal way of implementing the adapter for this? Should I use a single RecyclerView and assign the different adapters when searchView is focused and un-focused? Or should I use 2 RecyclerViews and show one while hiding the other? .
I understand that this may not be a very specific question, but I didn't want to risk implementing something which would not work optimally in the end. Any other suggestions are also welcome.
So I have a question about best practice for dynamically creating and sizing buttons within a ViewPager, based on a changing external state.
Essentially, I have a scrolling view and I want my ViewPager to contain a number of buttons of a specific size and count depending on what part of the scrolling view is currently visible.
My question is about deciding the best implementation of this feature, I see two options: would it be simpler to
Constantly create and scale new buttons whenever the scrolling view moves
Make the viewpager itself contain a scrollview and fill it with all of the pre-scaled buttons on app startup. Then, whenever the user scrolls the main scrollview the viewpager's scrollview (which contains the buttons) will scale programatically
Any ideas on which would be the simpler and more robust system?
Not much of an answer but I will leave a comment for ya! Basically you can do it either way, both aren't to difficult to accomplish, however I would probably go the dynamic route because it will always scale correctly. Doing a set amount will only work until devices become larger, or if you are targeting tablets or tvs then it will start to become extremely messy in the xml file for the layout. Dynamically adding also gives you far more control and saves time later on, you can simply change a number and have 100 more then going through and manually adding even 10. Hope this helps!
I am bit more concern of OOM on having a heavy UI on each item of a listview, example I have 100 items.
Below is the image that I wanted to practice and copy the UI layout. What would be the possible layout or how can I implement this type of UI. Each items are scrollable until the bottom, with separate contents but same layout. Please see my update below.
Update: I am planning to use card ListVIew, please guide me.
You can use simple listView or card ListView but make sure listView raw does not have many nested layout for avoiding nested hierarchy you should use Relative Layout in list raw
I think using a listview with custom row layout will be better for your app.This will help you to reuse the same layouts which are inflated when loading listview.Also please check the size of images you used in the rows.
I'm trying to create a basic UI for a simple Temperature Conversion app (new to android developing), and I can't figure out how to create a SINGLE page with two SEPARATE scrollable view pagers, one occupying the top half and the other occupying the bottom one.
I am using Eclipse. Feel free to ask for any other information required for your answer.
This is a rough drawing of what the layout should look like.
I'm trying to create a basic UI for a simple Temperature Conversion app
I do not know why a temperature conversion app would need one ViewPager, let alone two in the same activity at the same time.
I can't figure out how to create a SINGLE page with two SEPARATE scrollable view pagers, one occupying the top half and the other occupying the bottom one
In terms of the ViewPagers themselves, use a LinearLayout or something to vertically stack them.
Your bigger headache will come with the PagerAdapter implementations. At least one of these will have to be something other than FragmentPagerAdapter or FragmentStatePagerAdapter. Those implementations assume that they are the only such adapter for your activity, and I would expect that having two will cause collisions.
In my app i have a ListView with an ArrayAdapter. Every Item contains a picture, which takes a bit of time to render.
Now i want to add items dynamicly at the end of the List. The problem is, that wehenever add() is called my List blinks, because notifyDataSetChanged() is called and my pictures take a few milliseconds to render. I tried to avoid this by calling setNotifyOnChange(false). I solved the blinking with that, but unfortunately it is only updating the "length" of my list irregularly.
Is there some way to update the "length" of my listview, without updating the views which are shown?
I would agree that the UI thread should be avoided, especially for lists, and especially when using images for each list item.
Perhaps you need to find a more robust list adapter that is geared towards images? See this question for some helpful ideas/hints at how to improve your own list.
Also, the AndroidQuery (AQuery) library may be useful when fetching images for use in the arrayadapter: Image Loading via AQuery. It takes care of the burden of image caching as well, which I have found to be quite useful.