The list items are automatically inserted into the list using an adapter that is connected to a source, such as an array or a database query, and each item is converted into a row in the ListView. BaseAdapter, as it's name implies, is the base class for so many concrete adapter implementations on Android. It is abstract and therefore, cannot be directly instantiated.
If your data source is an ArrayList or array, we can also use the ArrayAdapter construct as an alternative. Note that ArrayAdapter itself extends from BaseAdapter. To use the BaseAdapter with a ListView, a concrete implementation the BaseAdapter class that implements the following methods must be created:.
Before we create our custom BaseAdapter implementation, we need to create the layout for the ListView row and also a model for the items in the ListView. Each of our ListView rows will conatain an Item name and Item description , so our Model class is as follows:. Once check that. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.
Learn more. Ask Question. Asked 10 years, 2 months ago. Active 10 years, 2 months ago. Viewed 4k times. Any ideas why this is happening? DisplayImage coverFileNames. So there may be some old tasks in the queue.
We need to discard them. NEW photoLoaderThread. Options ; options. Improve this question. Michell Bak. Michell Bak Michell Bak 13k 11 11 gold badges 60 60 silver badges bronze badges. Can you show some relevant code. Please check the updated answer, thanks. Try commenting out the line a. Also try commenting out imageView. This is the result: Just so you don't think I didn't try what you said: I did try it, it was just the same result as when setting an image resource, so I just copied that : — Michell Bak.
Add a comment. Active Oldest Votes. Which is really the case and does not need to be proven anyway Now Since this ImageView is a child of an Adapter interface, it is state of art that the Adapter's getView is called with the position of the exact view that contains this ImageView Finally, Worry Not because getView in this case is equivelant to invalidate and you surely want invalidate to be called so that your images show up.
This is normal. Advice : I believe one big bottleneck is your queuePhoto function which is always calling the Clean function! You are cleaning all the time!
Your key is an ImageView! Improve this answer. Sherif elKhatib Sherif elKhatib 45k 15 15 gold badges 86 86 silver badges bronze badges. It is not normal in this case.
It's not invalidating all the Imageviews twice, it's invalidating all once and the selected ImageView a lot of unneccessary times. In my getView implementation of the ArrayAdapter, I spawn a separate thread to load an image. After the loading is done, it looks up the appropriate ImageView and sets the image with ImageView.
So the solution I used is kind of similar to this one: Lazy load of images in ListView. The problem I'm having is that as soon as I make the call to setImageDrawable on the ImageView, the ListView somehow refreshes all currently visible rows in the list! This results in kind of an infinite loop:. So as far as I can see, the solution proposed in "Android - How do I do a lazy load of images in ListView" see link above simply doesn't work.
It might look like it does, but it will run very slow because in the background, it keeps reloading the currently visible rows. In the linked solution, fetchDrawableOnThread should only be called if the view does not already have the correct drawable.
If you are reusing slots, you views you need to go further and manage the state. If your views have a member variable storing the URL, and a boolean to say whether it is loaded, it'd be easy to know whether to call fetchDrawableOnThread or not, for example.
I'd speculate that the drawable's toString detailed the path from which the image was loaded. If it doesn't, you could subclass the drawable returned to make it so. In this case, you could avoid the boolean outlined above and just do a comparison to determine if its the right drawable or whether to fetch a replacement.
Additionally, your getView on a visible row should ensure that those that no longer visible get unloaded, to prevent memory exhaustion. A finesse would be to move the no longer visible images to soft references so they are unloaded when memory is needed as another poster on the original thread noted. Loading the images on a background thread is still a good idea. If you didn't want to reload them each time, I'd suggest setting up an NSMutableDictionary and storing the images in there.
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