how to fix go to next activity in adapter (Context.getPackageName()' on a null object reference)

Question

in my project i work by retrofit and make adapter & model
problem its after click on cardview for go to next activity , aplication crashed by error :

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
    at android.content.ComponentName.<init>(ComponentName.java:128)
    at android.content.Intent.<init>(Intent.java:5390)
    at ir.hmotamed.notline.adapter.NoteAdapter$1.onClick(NoteAdapter.java:54)
    at android.view.View.performClick(View.java:6261)

my adapter code :

public class NoteAdapter extends RecyclerView.Adapter<NoteAdapter.notesViewHoler> {


List<Querynotes> querynotes;
private Context mContext;

public NoteAdapter(List<Querynotes> querynotes, MainActivity mainActivity){

    this.querynotes=querynotes;

}

@NonNull
@Override
public notesViewHoler onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View view= LayoutInflater.from(parent.getContext()).inflate(R.layout.note_row,parent,false);
    return new notesViewHoler(view);

}

@Override
public void onBindViewHolder(@NonNull final notesViewHoler holder, int position) {

    final Querynotes queryPostses=querynotes.get(position);
    holder.title.setText(queryPostses.getTitle());
    holder.note.setText(queryPostses.getNote());
    holder.body.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            Intent intent=new Intent(mContext,EditNoteActivity.class);
            intent.putExtra("nid",queryPostses.getId());
            intent.putExtra("ntitle",queryPostses.getTitle());
            intent.putExtra("ndesc",queryPostses.getNote());
            mContext.startActivity(intent);

        }
    });

}

@Override
public int getItemCount() {

    return querynotes.size();

}

public class notesViewHoler extends RecyclerView.ViewHolder{

    int id;
    CardView parent;
    TextView title;
    TextView note;
    RelativeLayout body;
    public notesViewHoler(View itemView) {
        super(itemView);
        parent=itemView.findViewById(R.id.rv_note_row);
        title=itemView.findViewById(R.id.tv_header_title);
        note=itemView.findViewById(R.id.tv_body_desc);
        body=itemView.findViewById(R.id.rv_row_body);

    }
}

i need to after click click on my item go to next activity
but after click my app crashed and get error in line 54 for my adapter
line 54 it's :

Intent intent=new Intent(mContext,EditNoteActivity.class);

@ADM not duplicate ! that's not related int , but know fixed by `mohammadReza` answer — hmotamed, Apr 23 '19 at 13:11

score 1 · Accepted Answer · answered Apr 23 '19 at 13:00

1

you must initialize your context before use it:

public NoteAdapter(List<Querynotes> querynotes, MainActivity mainActivity){
mContext = mainActivity; \\ add this line
    this.querynotes=querynotes;

}

answered Apr 23 '19 at 13:00

mohammadReza Abiri

1,759
1
9
20

1

damet garm bro ;)! i did the same, but instead mainActivity i set Context! <3 – hmotamed Apr 23 '19 at 13:04
fadawt :) like yadet nare! – mohammadReza Abiri Apr 23 '19 at 13:05
1

montazeram time tamom beshe like konam :D – hmotamed Apr 23 '19 at 13:11
;) stack hang karde alan mige in dg che zabanie!! :) – mohammadReza Abiri Apr 23 '19 at 13:14

score 0 · Answer 2 · answered Apr 23 '19 at 13:01

Your context is null hence the crash. Make sure that you pass a context in the adapters constructor like this :

public NoteAdapter(List<Querynotes> querynotes, Context mContext){

    this.querynotes=querynotes;
    this.mContext=mContext;

}

and in your activity where you are creating the adapter :

NoteAdapter mNoteAdapter = new NoteAdapter(queryNotes, MainActivity.class);

how to fix go to next activity in adapter (Context.getPackageName()' on a null object reference)

2 Answers2