I am populating a ListView with images downloaded from URLs.
When I scroll the screen the images in the ListView take a moment or two to reappear.
How can I fix that?
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Codeman
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user3086226
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What do you mean they disappear? They're off the screen, why would they show up any more? I don't see anywhere that is declaring what the images are for each, do you do that in the Java code? – Codeman Jan 08 '14 at 22:52
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When I come back it has disappeared and reload again. – user3086226 Jan 08 '14 at 22:56
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Still not sure what you mean. Can you provide more details in your original question? – Codeman Jan 08 '14 at 23:00
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Oh, you mean they take a few moments to pop back in? – Codeman Jan 08 '14 at 23:06
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Take a look at this: http://stackoverflow.com/questions/541966/how-do-i-do-a-lazy-load-of-images-in-listview/3068012#3068012 – Codeman Jan 08 '14 at 23:07
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images load from url so It more than a few moments – user3086226 Jan 08 '14 at 23:08
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Right - check my answer, a lazy loader should solve your problem. I used the same method when grabbing images from a URL. – Codeman Jan 08 '14 at 23:10
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I've edited your question. Please post some code to help others out that find this. – Codeman Jan 08 '14 at 23:13
2 Answers
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I'm guessing you mean the images take a moment to load when you scroll back to them.
The reason this happens is because the Android system has reclaimed the resources that were used to hold these images in the current activity. You need to redownload them when you show them again. This is not ideal, as it looks slow to the user and uses more data.
You can get around this a bit easier with a lazy image loader. This keeps the images in memory, but does not download them until necessary (i.e. they are shown on the screen)
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Today, there are number of libraries that handle this exact issue, I found the Picasso
most convenient, I also wrote a blog post on this topic that I think you might find useful:
Guide: How to load images asynchronously into a ListView
You could could find there the most used libraries and code samples for how to use them.
Emil Adz
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