(RecyclerView) 尝试在空对象引用上调用虚拟方法“void android.widget.TextView.setText(java.lang.CharSequence)”

Question

I'm getting a null point exception while setting text..

my Fragment for recycler view

public class Product_Manual_Frag extends Fragment implements View.OnClickListener {

    //Database
    DBHelper db;
    Cursor myCursor = null;
    View rootView;
    // Cursor myCursor = null;
    List<RecyclerModel> data = fill_with_data();


    Pos_Ability_Activity main_Activity;

    public Product_Manual_Frag() {
        // Required empty public constructor
    }

    @Override
    public void onClick(View v) {

    }


    private List<RecyclerModel> fill_with_data() {
        List<RecyclerModel> data=new ArrayList<>();
        data.add(new RecyclerModel("Item1","10,000","2000","$"));
        data.add(new RecyclerModel("Item1","10,000","2000","$"));
        data.add(new RecyclerModel("Item1","10,000","2000","$"));
        data.add(new RecyclerModel("Item1","10,000","2000","$"));
        return data;

    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
       rootView = inflater.inflate(R.layout.fragment_poduct_manual, container, false);

        RecyclerView recycler=(RecyclerView)rootView.findViewById(R.id.my_recycler_view);
        RecyclerViewAdapter adapter=new RecyclerViewAdapter(data,getActivity());
        recycler.setLayoutManager(new LinearLayoutManager(getContext()));
        recycler.setAdapter(adapter);



        // Inflate the layout for this fragment
        return rootView;
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
    }

    @Override
    public void onDetach() {
        super.onDetach();
    }
}

my Recycleradapter

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.myViewholder> {
    List<RecyclerModel> data = Collections.emptyList();
    private LayoutInflater inflater;
    private Context context;

    public RecyclerViewAdapter(List<RecyclerModel> list, Context context) {
        this.context = context;
        inflater = LayoutInflater.from(context);
        this.data = list;
    }

    // Usually involves inflating a layout from XML and returning the holder
    @Override
    public myViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = inflater.inflate(R.layout.nav_drawer_row, parent, false);
        RecyclerViewAdapter.myViewholder holder = new RecyclerViewAdapter.myViewholder(view);
        return holder;
    }

    public void delete(int position) {
        data.remove(position);
        notifyItemRemoved(position);
    }

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
    }

    @Override
    public void onBindViewHolder(myViewholder holder, int position) {


        holder.txtPname.setText(data.get(position).Itemname);  //Getting  exception here

    } 




    @Override
    public int getItemCount() {
        return data.size();
    }




    class myViewholder extends RecyclerView.ViewHolder {
        RelativeLayout rl;
        TextView txtPname, txtorgprice, txtdisprice, txtcursym;
        CheckBox chkbx;

        public myViewholder(View itemView) {
            super(itemView);
            rl = (RelativeLayout) itemView.findViewById(R.id.relativeLayout1);
            txtPname = (TextView) itemView.findViewById(R.id.txtPName);
            txtorgprice = (TextView) itemView.findViewById(R.id.txtPOrgPrice);
            txtdisprice = (TextView) itemView.findViewById(R.id.txtPDisPrice);
            txtcursym = (TextView) itemView.findViewById(R.id.lblCurSym);
            chkbx = (CheckBox) itemView.findViewById(R.id.chkBox);

        }
    }

my model class

public class RecyclerModel {

    public String Itemname;
    public String ItempOrigrice;
    public String ItemdiscPrice;
    public String curSym;



    public RecyclerModel(String name, String orgprice, String DiscPrice, String currency) {
        this.curSym = currency;
        this.Itemname = name;
        this.ItempOrigrice = orgprice;
        this.ItemdiscPrice = DiscPrice;

    }

my fragment xml

    <?xml version="1.0" encoding="utf-8"?>
     <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/app_bg">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:scrollbars="vertical" />
</RelativeLayout>

my row_xml

    <?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relativeLayout1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">


    <ImageView
        android:id="@+id/imgIcon"
        android:background="@drawable/cashback"
        android:layout_width="50dp"
        android:layout_height="50dp"
        android:layout_alignParentLeft="true" />

    <TextView
        android:id="@+id/txtPName"
        android:text="Item name  sample"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toRightOf="@+id/imgIcon" />

    <TextView
        android:id="@+id/txtPOrgPrice"
        android:text="10,000 "
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtPName"
        android:layout_toRightOf="@+id/imgIcon" />

    <TextView
        android:id="@+id/lblCurSym"
        android:text="$"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtPOrgPrice"
        android:layout_toRightOf="@+id/imgIcon" />

    <TextView
        android:id="@+id/txtPDisPrice"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/txtPOrgPrice"
        android:layout_toRightOf="@+id/lblCurSym"
        android:paddingBottom="2dp"
        android:paddingRight="2dp"
        android:paddingTop="2dp"
        android:text="2,000 "
        android:textColor="#83410e"
        android:textSize="14sp" />

    <CheckBox
        android:id="@+id/chkBox"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_centerVertical="true" />


</RelativeLayout>

Am i missing something.?Please point the mistake i'm doing.

Answer 1

检查此布局： R.layout.nav_drawer_row最有可能的， txtPname为空。

Answer 2

Try this:

@Override
public myViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView= inflater.inflate(R.layout.nav_drawer_row, parent, false);
RecyclerViewAdapter.myViewholder holder = new RecyclerViewAdapter.myViewholder(itemView);
    holder.rl = (RelativeLayout) itemView.findViewById(R.id.relativeLayout1);
    holder .txtPname = (TextView) itemView.findViewById(R.id.txtPName);
    holder .txtorgprice = (TextView) itemView.findViewById(R.id.txtPOrgPrice);
    holder .txtdisprice = (TextView) itemView.findViewById(R.id.txtPDisPrice);
    holder .txtcursym = (TextView) itemView.findViewById(R.id.lblCurSym);
    holder .chkbx = (CheckBox) itemView.findViewById(R.id.chkBox);
return holder;
}
class myViewholder extends RecyclerView.ViewHolder {
RelativeLayout rl;
TextView txtPname, txtorgprice, txtdisprice, txtcursym;
CheckBox chkbx;

public myViewholder(View itemView) {
    super(itemView);
}
}

Answer 3

your adapter has R.layout.nav_drawer_row in

this method here :

@Override
public myViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.nav_drawer_row, parent, false);
    RecyclerViewAdapter.myViewholder holder = new RecyclerViewAdapter.myViewholder(view);
    return holder;
}

do this instead

@Override
public myViewholder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = inflater.inflate(R.layout.my_row_xml, parent, false);
    RecyclerViewAdapter.myViewholder holder = new RecyclerViewAdapter.myViewholder(view);
    return holder;
}

so if your referencing the wrong xml to the viewholder you are bound to get null pointer execption

do some research for on https://developer.android.com for recyclerview , you will get more ideas on how to use recyclerview

Answer 4

Check if R.layout.nav_drawer_row is the right layout in onCreateViewHolder.

Logically, if the instance of the TextView is null, the findViewById call in the holder returned null. One possible cause is trying to inflate a different layout~, by mistake, a one that dosen't have that specific id to be found. Take a look at the definition in https://developer.android.com/reference/android/app/Activity#findViewById(int)