Context - null object reference

Question

I have Fragment with RecyclerView adapter. Also i have month array and icluded posts array object.

I try to add posts table rows dinamically. I dont know how it should made.

public class NewsAdapter extends RecyclerView.Adapter<NewsAdapter.NewsCardViewHolder> {

private List<NewsMonth> months;
private List<NewsPost> posts;
private AdapterView.OnItemClickListener onItemClickListener;
private String TAG = "NewsAdapter";
private Context _context;
TableLayout tableLayout;

public NewsAdapter(List<NewsMonth> months, Context context) {
    this.months = months;
    this._context = context;
}

class NewsCardViewHolder extends RecyclerView.ViewHolder {
    CardView cv;
    TextView monthName;
    TextView postLabel;
    TextView postType;
    TableLayout tableLayout;

    NewsCardViewHolder(View itemView) {
        super(itemView);
        cv = itemView.findViewById(R.id.cv);
        monthName = itemView.findViewById(R.id.month_name);
        postLabel = itemView.findViewById(R.id.news_label);
        postType = itemView.findViewById(R.id.news_category);
        tableLayout = itemView.findViewById(R.id.tableNews);
    }
}

@NonNull
@Override
public NewsCardViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.news_item, viewGroup, false);
    return new NewsCardViewHolder(v);
}

@Override
public void onBindViewHolder(@NonNull NewsCardViewHolder ViewHolder, final int position) {
    ViewHolder.monthName.setText(months.get(position).getMonthName());
    posts = months.get(position).getPosts();
    for (int j = 0; j < posts.size(); j++) {
        //ViewHolder.itemView.addView(months.get(position).getPosts().get(j).getTitle());
        TextView postLabel = new TextView(_context.getApplicationContext());
        postLabel.setGravity(Gravity.START);
        postLabel.setText(months.get(position).getPosts().get(j).getTitle());
        postLabel.setLayoutParams(new TableRow.LayoutParams
                (LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT));
        postLabel.setTextSize(10);
        postLabel.setTextColor(Color.parseColor("#FF9900"));
        TableRow row = new TableRow(_context.getApplicationContext());
        row.addView(postLabel);
        tableLayout.addView(row);
    }
}

On activity start i get: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.Context android.content.Context.getApplicationContext()' on a null object reference on this line: TextView postLabel = new TextView...

EDIT:

public class NewsFragment extends Fragment{

private List<NewsMonth> monthArray;
private List<NewsPost> postArray;
private TableLayout tableLayout;

public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.news_fragment, container, false);
}

@Override
public void onViewCreated(@NonNull View view,
                          Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
    ViewPager viewPager = view.findViewById(R.id.view_pager);
    tableLayout = view.findViewById(R.id.tableNews);
    ImageSliderAdapter sliderAdapter = new ImageSliderAdapter(getContext());
    viewPager.setAdapter(sliderAdapter);
    initializeData();
    RecyclerView recyclerView = view.findViewById(R.id.newsList);
    recyclerView.setNestedScrollingEnabled(false);
    recyclerView.setHasFixedSize(false);
    recyclerView.setLayoutManager(new LinearLayoutManager(this.getActivity())); //getActivity(), LinearLayoutManager.VERTICAL, false
    NewsAdapter adapter = new NewsAdapter(monthArray, getContext());
    recyclerView.setAdapter(adapter);
    recyclerView.setItemAnimator(new DefaultItemAnimator());
}

Your _context will never be set – 0xPixelfrost Jul 23 '18 at 18:30 — 0xPixelfrost, Jul 23 '18 at 18:30

score 2 · Accepted Answer · answered Jul 23 '18 at 18:30

2

I think you need to set your _context correctly. Pass the context from the activity into the adapter then set _context to the context being passed.

public NewsAdapter(List<NewsMonth> months, Context context) {
    this.months = months;
    _context = context;
}

answered Jul 23 '18 at 18:30

Nigel Brown

440
2
13

now this error: TableLayout.addView(android.view.View)' on a null object reference – AlexS Jul 23 '18 at 18:40
is your adapter being called from a fragment is so sure you have correct refrence to the activities context – Nigel Brown Jul 23 '18 at 18:45
Yes, called by this line: NewsAdapter adapter = new NewsAdapter(monthArray, getContext()); I edit the question – AlexS Jul 23 '18 at 18:46
you need to put this.getActivity() insted of getContext – Nigel Brown Jul 23 '18 at 18:58
1

still null on addView – AlexS Jul 23 '18 at 19:09

Context - null object reference

1 Answers1