CODEWITHSUNDEEP
android
fhucho
fhucho

Reputation: 34550

SoftReference nulls too early

I have a bitmap cache in my Android app where the bitmaps are referenced via SoftReference. However the bitmaps are nulled too early. There can be 20 bitmaps max in the cache, if I load more, GC starts to null the SoftReferences. Without SoftReferences, I can have about 110 bitmaps in cache. Isn't SoftReference supposed to null just before OutOfMemoryError would happen?

Upvotes: 1

Views: 439

Answers (2)

cmcromance
cmcromance

Reputation: 2289

In my case, Hashmap(bitmap cache) got nulls if I got back from the other Activity. So, I fixed my code like below pseudo-code.

void displayImageFunction() {
    if(mImageCacheMap.containsKey(key)) {

        Bitmap bitmapToShow = mImageCacheMap.get(url).get();

        if(bitmapToShow != null) {
            //> Image was cached well
            //> Set "bitmapToShow" to UI
            return;
        }

    }

    //> Read from file DB(or Web) and... 
    Bitmap bmp = getBitmap(imageToLoad.url);

    //> put it to Hashmap again...
    mImageCacheMap.put(key, new SoftReference<Bitmap>(bmp));

    //> Set "bmp" to UI
}

I think we should prefare for nulls. Because, we cannot know when GC collects garbage. :)

Upvotes: 0

blubb
blubb

Reputation: 9910

No, the implication works the other way around:

It is guaranteed that the Java runtime will nullify SoftReferences, if any, before throwing a OutOfMemoryError. However, it does not guarantee that the SoftReference will get nullified only under this condition.

Upvotes: 5

Related Questions