android content Context getPackageName on a null object reference

Question

I am working with Fragments which implements an interface  public class SigninFragment extends Fragment implements SigninInterface   The interface s method implementation in the fragment class is as follows   Override public void afterSubmitClicked String userId  Bundle bundle         Log d TAG  quot Calling time afterSubmitClicked called quot  bundle            if  userId equals  quot -1 quot               Logged in successfully           Move to MusicHome                  Intent mIntent   new Intent getActivity   MusicHome class           mIntent putExtra  quot SigninFragment user details quot   bundle           startActivity mIntent                 else            Logging in failed           show error dialog               This method is called after exectuting a AsynchronousTask  which extends AsyncTask  class  But I am getting crash  And the error message shows java lang NullPointerException  Attempt to invoke virtual method  java lang String android content Context getPackageName    on a null object reference  Logcat    02-14 16 37 04 648  E AndroidRuntime 28177   Process  com raaga android  PID  28177 02-14 16 37 04 648  E AndroidRuntime 28177   java lang NullPointerException  Attempt to invoke virtual method  java lang String android content Context getPackageName    on a null object reference 02-14 16 37 04 648  E AndroidRuntime 28177      at android content ComponentName  lt init gt  ComponentName java 77  02-14 16 37 04 648  E AndroidRuntime 28177      at android content Intent  lt init gt  Intent java 3996  02-14 16 37 04 648  E AndroidRuntime 28177      at com raaga fragments SigninFragment afterSubmitClicked SigninFragment java 152  02-14 16 37 04 648  E AndroidRuntime 28177      at com raaga asynctask SignInAsyncTask onPostExecute SignInAsyncTask java 92  02-14 16 37 04 648  E AndroidRuntime 28177      at com raaga asynctask SignInAsyncTask onPostExecute SignInAsyncTask java 1  02-14 16 37 04 648  E AndroidRuntime 28177      at android os AsyncTask finish AsyncTask java 632  02-14 16 37 04 648  E AndroidRuntime 28177      at android os AsyncTask access 600 AsyncTask java 177  02-14 16 37 04 648  E AndroidRuntime 28177      at android os AsyncTask InternalHandler handleMessage AsyncTask java 645  02-14 16 37 04 648  E AndroidRuntime 28177      at android os Handler dispatchMessage Handler java 102  02-14 16 37 04 648  E AndroidRuntime 28177      at android os Looper loop Looper java 135  02-14 16 37 04 648  E AndroidRuntime 28177      at android app ActivityThread main ActivityThread java 5221  02-14 16 37 04 648  E AndroidRuntime 28177      at java lang reflect Method invoke Native Method  02-14 16 37 04 648  E AndroidRuntime 28177      at java lang reflect Method invoke Method java 372  02-14 16 37 04 648  E AndroidRuntime 28177      at com android internal os ZygoteInit MethodAndArgsCaller run ZygoteInit java 899  02-14 16 37 04 648  E AndroidRuntime 28177      at com android internal os ZygoteInit main ZygoteInit java 694

User · Answer

For me the problem was that I was passing Activity to the constructor, not Context

public Adapter(Activity activity, List<MediaItem> items, boolean can) {
    mItems = items;
    canEdit = can;
    mActivity = activity;
}

and using this activity to getDefaultSharedPreferences(), so I changed the Activity to Context and I was still calling the Adapter constructor with MainActivity.this

User · Answer

I had the same problem trying to show a Toast in a fragment   After some debugging I found out that I was removing the fragment before calling   Toast makeText getContext     text   Toast LENGTH SHORT  show      Because the fragment had been removed  the context became null  causing the exception   Simple solution  call the getContext   before removing the fragment

User · Answer

android API level 23   Use      getContext     instead of      getActivity     getActivity    gives the parent Activity  a Context object   Here You can use      MyActivity this   instead of      getActivity     getApplicationContext

User · Answer

Use can use in global Context context   and create a constructor and passing the context  LoginClass is name of the class LoginClass Context context   this context context    and also when we call the class then use getApplicationContext like LoginClass lclass    new LoginClass getApplicationContext  thats it

User · Answer

You solve the issue with a try  catch  This crash happens when user close the app before the start intent   try       Intent mIntent   new Intent getActivity   MusicHome class       mIntent putExtra  SigninFragment user details   bundle       startActivity mIntent     catch  Exception e        e printStackTrace

User · Answer

My class is not extends to Activiti  I solved the problem this way   class MyOnBindViewHolder   LogicViewAdapterModel LogicAdapter                  holder title setOnClickListener  v- gt                  v context startActivity Intent context   HomeActivity  class java

User · Answer

You can solve your problem easily and use your activity anywhere in the activity  just store activity like this    public class MainActivity extends AppCompatActivity        Context context   this         protected void onCreate Bundle savedInstanceState                AnotherClass             Intent intent   new Intent context  ExampleActivity class             intent putExtra  key    value              startActivity intent

User · Answer

In my case I had a onCLick method in a recyclerview adapter Context context  at the beginning    holder cTextView setOnClickListener new View OnClickListener                      Override                 public void onClick View v                        Intent intent   new Intent context  StoryActivity class                       intent putExtra  STORY   mComments get position                        context startActivity intent                                       And i changed to get the context from the current view   holder cTextView setOnClickListener new View OnClickListener                      Override                 public void onClick View v                        Intent intent   new Intent v getContext    StoryActivity class                       intent putExtra  STORY   mComments get position                        v getContext   startActivity intent

User · Answer

I have found the mistake what I did   We need to get the activity instance from the override method OnAttach   For example   public MainActivity activity    Override public void onAttach Activity activity       this activity   activity      Then pass the activity as context as following    Intent mIntent   new Intent activity  MusicHome class

User · Answer

The answers to this question helped me find my problem  but my source was different  so hopefully this can shed light on someone finding this page searching for answers to the  random  context crash  I had specified a SharedPreferences object  and tried to instantiate it at it s class-level declaration  like so  public class MyFragment extends FragmentActivity       private SharedPreferences sharedPref           PreferenceManager getDefaultSharedPreferences this     Override protected void onCreate Bundle savedInstanceState        super onCreate savedInstanceState              Referencing this before the onCreate caused the  quot java lang NullPointerException  Attempt to invoke virtual method  java lang String android content Context getPackageName    on a null object reference quot  error for me  Instantiating the object inside the onCreate   solved my problem  like so  public class MyFragment extends FragmentActivity       private SharedPreferences sharedPref        Override     protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState                         sharedPref   PreferenceManager getDefaultSharedPreferences this    Hope that helps

User · Answer

You only need to do this   Intent myIntent   new Intent MainActivity this  nextActivity class

User · Answer

In my case the error occurred inside a Fragment on this line   Intent intent   new Intent getActivity    SecondaryActivity class     It happened when I double clicked on an item which triggered the code above so two SecondaryActivity class activities were launched at the same time  one on top of the other  I closed the top SecondaryActivity class activity by pressing back button which triggered a call to getActivity   in the SecondaryActivity class which came to foreground  The call to getActivity   returned null  It s some kind of weird Android bug so it usually should not happen  You can block the clicks after the user clicked once

User · Answer

public MessageAdapter Context context  List lt Messages gt  mMessageList         this mContext   context      this mMessageList   mMessageList

User · Answer

Put fragment name before the activity  Intent mIntent   new Intent SigninFragment this getActivity   MusicHome class

User · Answer

Due to onAttach is deprecated in API23 and above    In my Fragment  I declare and set parentActivity before hand everytime when I go into Fragment  Most likely happen due to when we pressed back button caused the context to become null  Therefore below is my solution   private Activity parentActivity   public void onStart            super onStart            parentActivity   getActivity

[android] android.content.Context.getPackageName()' on a null object reference

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