The Android developer site also explains why SoftReference and WeakReference are no longer a good solution. It also goes into detail on how to developer a good solution: http://developer.android.com/training/displaying-bitmaps/cache-bitmap.html
"In the past, a popular memory cache implementation was a SoftReference<http://developer.android.com/reference/java/lang/ref/SoftReference.html> or WeakReference<http://developer.android.com/reference/java/lang/ref/WeakReference.html> bitmap cache, however this is not recommended. Starting from Android 2.3 (API Level 9) the garbage collector is more aggressive with collecting soft/weak references which makes them fairly ineffective." On Thu, Apr 26, 2012 at 11:49 AM, bruce <palant...@gmail.com> wrote: > I found that the soft references works when you are dealing with > smaller allocations but if you deal with images, it gc()'s the > reference took quick for it to be useful. There used to be some > control around what thresholds are used but that isn't a good way to > do it anyway. My solution was to go ahead and implement an LRU cache > with hashmap and software references as Daniel mentions. Then I have > a subset of that which are have hard references to a minimal number. > That way, I don't get immediately gc'd and for systems that work > better I get the benefit. If an OutOfMemoryError occurs, I can flush > the cache, perform a couple of gc() calls, and continue. After doing > some performance analysis of the rest of the code, minimizing memory > churn, making sure bitmaps are manually recycled, reduced these errors > greatly. I would suggest using TraceView and MemoryAnalyzer to make > sure you really are releasing properly and just to see how the app is > performing in general. You might spot some problems. > > On 3.0+ devices you can add to your AndroidManifest, in the > <application /> area: 'android:largeHeap="true"'. This gives lots > of room for large pics (256M I believe). I wouldn't use it if you use > mostly small allocations because there is a performance hit with the > large heap. > > Cheers, > Bruce > > > On Apr 26, 4:01 am, Daniel Drozdzewski <daniel.drozdzew...@gmail.com> > wrote: > > The thing is that Android OS will allocate the memory according to the > > needs of a process (up to maximum memory allowed). > > > > So, if were able to establish the amount of free memory that your app > > has available, the OS might increase this allowance as soon as you > > allocate next bitmap, therefore the whole method makes little sense. > > > > Instead build a HashMap that uses soft references to build a primitive > > cache with random eviction policy. The bitmaps will get removed as the > > process is running low on memory. There are few good articles about > > the usage of soft and weak references to implement primitive caches in > > Java. This gives you a solution that will adapt to whatever memory > > allowance is there (different per OS version) with all the memory > > management duties shifted to the platform. > > > > Here is one such article: > http://www.javaspecialists.eu/archive/Issue015.html > > > > Daniel > > > > On 25 April 2012 16:57, Anieeh <animesh.andr...@gmail.com> wrote: > > > > > > > > > > > > > > > > > > > > > Hi all > > > I am having problem with releasing memory problem, i have a > > > Hashmap in which i am adding Bitmap object, and the no. of bitmaps are > > > quite large. for this reason i am getting "OutOfMemoryError". So for > > > this i have decided to release Bitmap whic is least used from > > > Collection, on memory crunch or system getting low heap memory. > > > For getting current memory available i used > > > "ActivityManager.MemoryInfo.availMem" but it gives total RAM size > > > memory, not Available Heap memory. And i found that this memory is not > > > getting updated on releasing Bitmap from collection. > > > > > Then i have used these three method > > > "Debug.getNativeHeapAllocatedSize()" > > > "Debug.getNativeHeapFreeSize()" > > > "Debug.getNativeHeapSize()" > > > > > but found the NativeHeapSize goes on increasing upto some certain say > > > 16MB changing after that an "outOfMemoryError" occur. In this also i > > > found that the NativeHeapAllocatedSize and getNativeHeapSize not > > > decreasing on releasing Bitmap from collection. > > > > > So please help me for solving the problem if anyone facing the same > > > problem and fixed earlier it. > > > > > My problem is i want to calculate "Max Available application memory > > > allocated" and "currently available memory", for such that if > > > "currently available memory" goes beyond the Threshold memory i will > > > release some Bitmap from the collection and GC will reclaim the memory > > > and free it without generating error. > > > > > Thanks in advance > > > Anieeh > > > > > -- > > > You received this message because you are subscribed to the Google > > > Groups "Android Developers" group. > > > To post to this group, send email to > android-developers@googlegroups.com > > > To unsubscribe from this group, send email to > > > android-developers+unsubscr...@googlegroups.com > > > For more options, visit this group at > > >http://groups.google.com/group/android-developers?hl=en > > > > -- > > Daniel Drozdzewski > > -- > You received this message because you are subscribed to the Google > Groups "Android Developers" group. > To post to this group, send email to android-developers@googlegroups.com > To unsubscribe from this group, send email to > android-developers+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/android-developers?hl=en > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. 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