Java – What’s wrong with this bitmap’s inSampleSize calculation method? Out of memory

In my application, I iterate through the URLs of images, decode them, and put them into an ArrayList<Bitmap>

Their sizes can vary greatly, so I’m using the inJustDecodeBounds = true for the “pre-decode” option to calculate the value of the necessary inSampleSize to actually decode.

Check out my method below, I hope it’s not too hard to understand. Basically, my goal is to be similar in size to the screen of the device.

for (Element e: posts) {
    if (!e.id().equals("")) {
        preparing decode
        options = new BitmapFactory.Options();
        input = new URL(e.url).openStream();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(input, null, options);
        input.close();

setting inSampleSize if necessary
        int picPixels = options.outWidth * options.outHeight;
        int picScreenRatio = picPixels / screenPixels;
        if (picScreenRatio > 1) {
            int sampleSize = picScreenRatio % 2 == 0 ? picScreenRatio : picScreenRatio + 1;
            options.inSampleSize = sampleSize;
        }

actual decode
        input = new URL(e.url).openStream();
        options.inJustDecodeBounds = false;
        Bitmap pic = BitmapFactory.decodeStream(input, null, options);
        input.close();

picList.add(pic);
    }
}

Code to calculate screenPixels:

Display display = getWindowManager().getDefaultDisplay();
Point screenSize = new Point();
display.getSize(screenSize);
int screenPixels = screenSize.x * screenSize.y;

I’m looking at about 60 images, of which about 40 of my app crashes with java.lang.OutOfMemoryError

As I understand it,

no memory is allocated with inJustDecodeBounds = true, and if my approach is correct (I believe it is), very large images become very large inSampleSize s, so I don’t know what the problem might be.

Any suggestions would be appreciated.

Whether you use inSampleSize, you can’t easily fit 60 bitmaps as large as a screen in memory.

Assuming a Full HD screen you get about 1920*1080*60*4 bytes.

This is approximately 500 MB of data.
You need to change your bitmap loading logic somehow.

In this Answer: You can find out how much memory you can count. It varies depending on various devices.

But always try to make your app as memory efficient as possible.