Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()

Question

I am using PreferenceManager in one of my fragment using codes like this.

String userId = PreferenceManager.getDefaultSharedPreferences(getContext()).getString("userId", "");

Its causing some time error called above. I have searched many questions in stackflow but not able to fix it. My complete error log is like below

FATAL EXCEPTION: main
Process: com.example.shayari, PID: 29366
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
at android.support.v7.preference.PreferenceManager.getDefaultSharedPreferencesName(PreferenceManager.java:308)
at android.support.v7.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java:303)
at com.example.shayari.material.QuotesListFragment.updateQuotesListServer(QuotesListFragment.java:252)
at com.example.shayari.material.QuotesListFragment.access$900(QuotesListFragment.java:45)
at com.example.shayari.material.QuotesListFragment$4.onResponse(QuotesListFragment.java:202)
at retrofit2.ExecutorCallAdapterFactory$ExecutorCallbackCall$1$1.run(ExecutorCallAdapterFactory.java:70)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6290)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Anyone have faced similar issue and if found any solution, let me know. Thanks a lot

CommonsWare · Accepted Answer · 2017-07-29 18:10:16Z

1

getContext() is returning null. It will do that when the fragment is no longer attached to the activity.

You seem to be making a Retrofit call from a fragment and are attempting to update SharedPreferences as part of processing the response. However, apparently, you are not checking to see if the fragment is still attached to the activity. There are many reasons why the fragment may have been detached, including navigation (e.g., user presses BACK to exit the activity before the network I/O is complete) or configuration changes (e.g., the user rotates the screen, causing Android to swap to a new activity and new fragment, but Retrofit still wants to talk to the old fragment).

answered Jul 29, 2017 at 18:10

CommonsWare

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