Android "Trying to use recycled bitmap" error?

Question

I am running into a problem with bitmaps on an Android application I am working on. What is suppose to happen is that the application downloads images from a website, saves them to the device, loads them into memory as bitmaps into an arraylist, and displays them to the user. This all works fine when the application is first started. However, I have added a refresh option for the user where the images are deleted, and the process outlined above starts all over.

My problem: By using the refresh option the old images were still in memory and I would quickly get OutOfMemoryErrors. Thus, if the images are being refreshed, I had it run through the arraylist and recycle the old images. However, when the application goes to load the new images into the arraylist, it crashes with a "Trying to use recycled bitmap" error.

As far as I understand it, recycling a bitmap destroys the bitmap and frees up its memory for other objects. If I want to use the bitmap again, it has to be reinitialized. I believe that I am doing this when the new files are loaded into the arraylist, but something is still wrong. Any help is greatly appreciated as this is very frustrating. The problem code is below. Thank you!

public void fillUI(final int refresh) { 
// Recycle the images to avoid memory leaks
if(refresh==1) {
    for(int x=0; x<images.size(); x++)
        images.get(x).recycle();
    images.clear();
    selImage=-1; // Reset the selected image variable
}
final ProgressDialog progressDialog = ProgressDialog.show(this, null, this.getString(R.string.loadingImages));
// Create the array with the image bitmaps in it
new Thread(new Runnable() {
    public void run() {
        Looper.prepare();
        File[] fileList = new File("/data/data/[package name]/files/").listFiles();
        if(fileList!=null) {
            for(int x=0; x<fileList.length; x++) {
                try {
                    images.add(BitmapFactory.decodeFile("/data/data/[package name]/files/" + fileList[x].getName()));
                } catch (OutOfMemoryError ome) {
                    Log.i(LOG_FILE, "out of memory again :(");
                }
            }
            Collections.reverse(images);
        }
        fillUiHandler.sendEmptyMessage(0);
    }
}).start();

fillUiHandler = new Handler() {
    public void handleMessage(Message msg) {
        progressDialog.dismiss();
    }
};

}

Answer 1

You don't actually need to call recycle method here. Refresh button should just clear the array, garbage collector will free the memory later. If you get OutOfMemory it means some other objects are still referencing your old images and Garbage Collector can't remove them.

I may asume that some ImageViews display your bitmaps and they keep references to that bitmaps. You can't remove old bitmaps while they're still displayed. So a possible solution is to clear ImageVIews too. After that you can clear the array and fill it with new images.

Recycle frees the memory but some ImageView is still displaying the bitmap and it can't do that after recycle, that's why you get "Trying to use recycled bitmap".

These all are just an assumptions because I can't see your complete code.

Answer 2

If the memory is very large, you'd better recycle the bitmap yourself. GC can't be controled.