Android - hold data in memory with WeakReference

Question

I have simple DataHolder class:

public class DataHolder
{
    private static final DataHolder holder = new DataHolder();
    Map<String, WeakReference<Object>> data = new HashMap<>();

    public static DataHolder getInstance() {return holder;}

    public void save(String id, Object object)
    {
        data.put(id, new WeakReference<>(object));
    }

    public Object retrieve(String id)
    {
        WeakReference<Object> objectWeakReference = data.get(id);
        return objectWeakReference.get();
    }
}

Basically, I want to hold some data to retrieve them anywhere else (for example, other activity or fragment).

To save:

DataHoler.getInstance().save("list", myList);

To retrieve data:

List<MyObject> list = (ArrayList) DataHoler.getInstance().retrieve("list");

My intent is to avoid passing large amount of data with parcelable (this should be avoided, list may be large) + simplify access to data between all activities/fragments.

Is my approach correct? Not sure if it won't cause any unexpected behaviours or memory leaks.

score 0 · Answer 1 · answered Apr 16 '19 at 10:27

0

This approach working well in case of less data, but when large data come in the memory at that time app may not respond properly

answered Apr 16 '19 at 10:27

Taufik Mira

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1

What is "large"? For example, list containing 1000 objects, each objects 10 fields. – user1209216 Apr 16 '19 at 10:37

score 0 · Answer 2 · answered Apr 16 '19 at 10:31

0

you can use shared preference to store data. i am adding a link of my previous answer it will be help your answer look this link :- Updating an object stored in one Activity from another activity

answered Apr 16 '19 at 10:31

Sandeep Malik

1,972
1
8
17

This will be very slow – user1209216 Apr 16 '19 at 10:42
why this is slow ? – Sandeep Malik Apr 16 '19 at 10:42
Disk caching, especially in shared prefs is very slow for large data. – user1209216 Apr 16 '19 at 10:43
shared preference is not for large data it is used for single time small data if you want to store havy data then you can create RoomDatabse in your app or connect with server – Sandeep Malik Apr 16 '19 at 10:44
Yes, RoomDatabase is fine, howver it's far too big as only to pass list to another activity. And it will be still slower than memory cache + implementation is complicated – user1209216 Apr 16 '19 at 10:46
if my answer helps you then appriciate the answer – Sandeep Malik Apr 16 '19 at 10:47
Actually, I know shared preferences, but it's definitely not an option in this case, 2 reasons: very slow and I first need to serialize it (to json for example) and deserialize again, next slow down. – user1209216 Apr 16 '19 at 10:50
then what is best thing to store small data in your app ? – Sandeep Malik Apr 16 '19 at 10:53
As long as it does not need to survive application restart, not save or keep in memory – user1209216 Apr 16 '19 at 10:55
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/191909/discussion-between-sandeep-malik-and-user1209216). – Sandeep Malik Apr 16 '19 at 10:57

score 0 · Answer 3 · answered Apr 16 '19 at 10:31

0

I recommend using SoftReference, it is better for caching, objects will live longer. What if GC removes data which you actually needed? WeakReference or SoftReference object can be removed by GC anytime.

answered Apr 16 '19 at 10:31

Marek Kondracki

1,372
2
8
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Won't GC know if data is needed or not in this case? – user1209216 Apr 16 '19 at 10:33
Solution taken from: https://stackoverflow.com/questions/4878159/whats-the-best-way-to-share-data-between-activities/45157829 as far as I understand, GC should not delete it as long as activity that created data exists. This should be garbage collected after activity destroy. – user1209216 Apr 16 '19 at 10:40

Android - hold data in memory with WeakReference

3 Answers3