Android WeakReference

Question

I have an activity where i have to trigger from place to place a custom pop-up dialog which is also a singleton

From my activity i open the pop-up :

  ScheduleDialog.getInstance().refreshContent(new WeakReference<Context>(this), new WeakReference<ScheduleDialog.interface>(this));

What is best ? 1) create 2 local references ( in ScheduleDialog ) like :

   Context mContext = nContext.get();

2) keep both like weak reference and only when i need them use :

nContext.get();

This is related about leaks error/warnings

Thanks

You did not explain why you are using `WeakReference` for context (if in fact you can use Application context) and also show the ScheduleDialog code (otherwise we do not know if your code is leaky). — Enzokie, Feb 08 '18 at 12:33

duggu · Accepted Answer · 2018-02-08T12:44:51.683

1

If I see your code you create strong reference again after get weak reference value in Context nContext variable. So need to follow below process if you want to implement weak reference concept :-

define global class variable :-

private final WeakReference< Context > nContext;

set value in global variable through passing from another area

nContext = new WeakReference<Context>(nContext);

and then

if (nContext.get() != null) 
    // code
}

https://medium.com/google-developer-experts/weakreference-in-android-dd1e66b9be9d

edited Feb 08 '18 at 12:44

answered Feb 08 '18 at 12:36

duggu

37,851
12
116
113

I think you mean `member variable` cuz we [don't](https://stackoverflow.com/questions/5581234/why-are-there-no-global-variables-in-java) have global variable in Java. – Enzokie Feb 08 '18 at 12:42
so you are pointing on the second option but with a little update : ScheduleDialog.getInstance().refreshContent(this,this) with the help of your article. Right ? – BejanCorneliu Feb 08 '18 at 12:47
@user863873 honestly I don't see the point of using WeakReference not unless your dialog can outlive your view like for example how Thread does (that's the only case you worry for leak). – Enzokie Feb 08 '18 at 12:55
i see your point. May be is a dummy question but : what if i have multiple activities and each one has recyclerview + adapter. If i use weakreference in each adapter if there will be memory problem ... only the adapter(s) will be GC. Or this is not possible because adapter is a member variable in activity and if memory problem also the activity will be GC ? – BejanCorneliu Feb 08 '18 at 13:07
@user863873 if your activity is destroyed your Adapter and RecyclerView will also be Garbage collected (since your activity is the only the one holding the reference to them not unless a *static* reference is holding them or a background Thread itself). You could experiment this using [LeakCanary](https://github.com/square/leakcanary). – Enzokie Feb 09 '18 at 03:32

score 0 · Answer 2 · answered Feb 08 '18 at 12:42

0

You have to keep them as WeakReferences, otherwise the Garbage Collector will see there are strong references to the object and won't collect them, leading to the leak you mentioned.

answered Feb 08 '18 at 12:42

Juan

5,525
2
15
26

Android WeakReference

2 Answers2