How do I download Bitmaps and save to the SD card without running out of memory?

Question

I'm looking for the best way to download an array of Bitmaps, modify them a bit and then save to the SD card.

I've heard that ByteArrayOutputStream is a bad idea to use because it loads the image into the RAM of the device. Instead I'm probably supposed to use something like a BufferedInputStream and FileOutputStream, however I don't know how I can alter the Bitmaps before saving them using this method.

Thanks

score 1 · Answer 1 · edited Jun 26 '13 at 20:06

1

You can create your bitmap from your InputStream using:

Bitmap bm = BitmapFactory.decodeStream(inputStream);

and then after you have processed your Bitmap and stored them you must use:

bm.recycle();
bm = null;

to avoid OutOfMemoryExceptions .

EDIT:

For writing it to a file:

OutputStream fos=new BufferedOutputStream(new FileOutputStream(filePath));
byte buf[]=new byte[1024];
int len;
while((len=is.read(buf))>0)
    fos.write(buf,0,len);
fos.close();
is.close();

edited Jun 26 '13 at 20:06

jenzz

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answered Aug 03 '11 at 11:41

Ovidiu Latcu

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Yes, thanks, I know that, but how do I write the Bitmap to a file on the SD Card without using the ByteArrayOutputStream? – Michell Bak Aug 03 '11 at 15:25
Thanks for that - but your code is reading directly from the inputStream and not the Bitmap :( – Michell Bak Aug 03 '11 at 15:53

score 1 · Accepted Answer · edited May 23 '17 at 11:47

1

You will not like the answer: you cannot (at least, not with the Android framework).

The only option is to downscale the image so that it fits in memory; and regularly call recycle()and System.gc() to free memory as soon as possible.

edited May 23 '17 at 11:47

Community

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answered Aug 03 '11 at 16:42

rds

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Yeah, that's pretty much what I feared. I guess what I can do is download the images using a BufferedInputStream and then do my Bitmap manipulating afterwards. Not the best thing in the world, but luckily I was downloading the images using an AsyncTask, so I'll be able to do the Bitmap stuff in the onPostExecute() method. Thanks a lot :) – Michell Bak Aug 03 '11 at 17:25
And then another recommendation: implement your long running tasks (downloading, image manipulation) with an `IntentService` rather than an `AsyncTask` (see http://stackoverflow.com/questions/2620917/how-to-handle-an-asynctask-during-screen-rotation http://www.google.com/events/io/2010/sessions/developing-RESTful-android-apps.html) – rds Aug 04 '11 at 08:25

How do I download Bitmaps and save to the SD card without running out of memory?

2 Answers2