getSharedPreferences return Null pointer exeption on some devices

Question

I have App on Google play, on most devices it work just fine but seems like it on some Samsung(SM-G531H,SM-G530BT), HUAWEI, Lenovo devices it crashes when getSharedPreferences calls.

I take a reference to context from onAttach(Context context) in fragment method (i am not calling getSharedPreferences before onAttach)

@Override
    public void onAttach(Context context) {
        super.onAttach(context);

        mContext = context;
        //init firebase analytics
        mFirebaseAnalytics = FirebaseAnalytics.getInstance(context);
    }

I have sharedPreference helper class with constructor

 public UserStats(Context mContext) {

    CRASH HERE

        sharedPreferences = mContext.getSharedPreferences(PREF_USER,Context.MODE_PRIVATE); 

        }

This is the method in fragment that invoke sharedPreference

private void setGoal(int calories){
        new UserStats(mContext).setNewGoal(calories);

        tvGoal.setText("Goal\n" + calories + " Cal");
    }

Any idea why it happen? and how to avoid it? (i cannot debug it i receive crashes in Firebase console)

Hey, I'm seeing inconsistencies in `onAtttach()` calls as mentioned [here](https://stackoverflow.com/questions/32077086/android-onattachcontext-not-called-for-api-23). Did you check that out? I'd say look for alternatives. — Shaishav, Jul 10 '17 at 07:54
interesting, but i used getActivity() before and was the same result — Pavel Poley, Jul 10 '17 at 08:04
Where are you calling that `setGoal()` method? If it's as a result of some async operation, the fragment might already be detached from its activity and the activity might be gone and all you're left with is a stale context reference. — laalto, Jul 10 '17 at 08:13
Where do you call `setGoal()` from? Also a minor suggestion, in your constructor for `UserStats`, don't precede the parameter name with `m`. Thats against the [code-style-guide](https://source.android.com/source/code-style). — Shaishav, Jul 10 '17 at 08:13
setGoal() called in onViewCreated() in fragment (there is no click or long delay that call this method) — Pavel Poley, Jul 10 '17 at 08:17
`mContext` is not a useful variable, you should call `getContext()` instead which already keeps track of the fragment's current context. If you still get a crash please provide the full stack trace. — BladeCoder, Jul 13 '17 at 12:29
Ok, i will try to change to getContext, but Why mContext is not usefull? Also Why getActivity not usefull? — Pavel Poley, Jul 13 '17 at 12:50
Note that if in `setGoal()` you cannot use `getContext()`, then maybe `tvGoal` member will be not initialized, too. — Alex Cohn, Jul 16 '17 at 10:47

score 2 · Answer 1 · answered Jul 10 '17 at 07:38

2

use getApplicationContext() always if available

answered Jul 10 '17 at 07:38

Rasoul Miri

11,234
1
68
78

Not always. If you want Activity-specific preferences, use the Activity Context. – BladeCoder Jul 13 '17 at 14:17

score 0 · Answer 2 · answered Jul 10 '17 at 07:36

0

Use getActivity() in replace of mContext. It does not find fragment's referrence. So , app is crashed.

answered Jul 10 '17 at 07:36

Vishal Vaishnav

3,346
3
26
57

1

i have used getActivity() before, same result i received the same crashes – Pavel Poley Jul 10 '17 at 07:39

score 0 · Accepted Answer · answered Jul 10 '17 at 07:42

0

If you are in activity use getApplicationContext() .

If you are in fragment use getContext() .

If you are in adapter class use context and add Context parameter of adapter's constructor.

answered Jul 10 '17 at 07:42

Kuldeep Jindani

123
8

getSharedPreferences return Null pointer exeption on some devices

3 Answers3