如何在Android中的RecyclerView上添加onClickListener？
我正在开发一个租车应用程序。当用户点击汽车上的按钮时，他应该被引导到预订页面。我尝试了那里的一切，但当我单击视图/汽车时，我得到以下错误：如何在Android中的RecyclerView上添加onClickListener？,android,Android,我正在开发一个租车应用程序。当用户点击汽车上的按钮时，他应该被引导到预订页面。我尝试了那里的一切，但当我单击视图/汽车时，我得到以下错误： java.lang.NullPointerException:尝试在空对象引用上调用接口方法'void com.cuboid.rentacabs.ViewAdapter$onClickListener.onClick（int）' 代码中的所有内容在我看来都很好， 这是我的viewAdapter.java public class ViewAdapter ex
java.lang.NullPointerException:尝试在空对象引用上调用接口方法'void com.cuboid.rentacabs.ViewAdapter$onClickListener.onClick（int）'public class ViewAdapter extends RecyclerView.Adapter<ViewAdapter.MyViewHolder> {
DatabaseReference ref;
FirebaseDatabase fbRref;
Context context;
ArrayList<Model> model;
private onClickListener mListener;
public ViewAdapter(Context c, ArrayList<Model> listItems, onClickListener onClickListener)
{
this.context = c;
this.model = listItems;
this.mListener = onClickListener;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
LayoutInflater inflater = LayoutInflater.from(context);
View view = inflater.inflate(R.layout.car_details, parent, false);
fbRref = FirebaseDatabase.getInstance();
ref = fbRref.getReference();
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
holder.carName.setText(model.get(position).getmCarName());
holder.seatingCapacity.setText(model.get(position).getmSeatingCapacity());
holder.transmission.setText(model.get(position).getmTransmission());
holder.fuelType.setText(model.get(position).getmFuelType());
//holder.rate.setText(model.get(position).getmRate());
}
@Override
public int getItemCount() {
return model.size();
}
public static class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener
{
public TextView carName,seatingCapacity,transmission,fuelType,rate;
public Button bookBtn;
public onClickListener onClickListener;
public MyViewHolder(@NonNull View itemView)
{
super(itemView);
carName = itemView.findViewById(R.id.car_name);
seatingCapacity = itemView.findViewById(R.id.seating_capacity);
transmission = itemView.findViewById(R.id.transmission_type);
fuelType = itemView.findViewById(R.id.fuel_type);
rate = itemView.findViewById(R.id.rate);
bookBtn =(Button) itemView.findViewById(R.id.book_btn);
itemView.setOnClickListener(this);
}
@Override
public void onClick(View v) {
onClickListener.onClick(getAdapterPosition());
}
}
public interface onClickListener
{
void onClick(int position);
}
public class home extends Fragment implements ViewAdapter.onClickListener{
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public home() {
}
// TODO: Rename and change types and number of parameters
public static home newInstance() {
home fragment = new home();
Bundle args = new Bundle();
fragment.setArguments(args);
return fragment;
}
//to recycler view.
private RecyclerView recyclerView;
public View view;
private ArrayList<Model> listItem;
ViewAdapter Vadapter;
DatabaseReference dbRef;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
view = inflater.inflate(R.layout.fragment_home, container,false);
recyclerView = view.findViewById(R.id.carDetailsContainer);
listItem = new ArrayList<Model>();
RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getContext());
recyclerView.setLayoutManager(layoutManager);
dbRef = FirebaseDatabase.getInstance().getReference().child("Cars");
Vadapter = new ViewAdapter(getContext(),listItem,this);
//recyclerView.OnClickListener();
return view;
}
@Override
public void onStart() {
super.onStart();
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot ds : dataSnapshot.getChildren())
{
Model model = new Model(ds.child("Name").getValue().toString(),ds.child("Seating_Capacity").getValue().toString(),ds.child("Fuel").getValue().toString(),ds.child("Transmission").getValue().toString(),ds.child("Rate").getValue().toString());
listItem.add(model);
}
recyclerView.setAdapter(Vadapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
};
dbRef.addValueEventListener(valueEventListener);
}
@Override
public void onClick(int position) {
listItem.get(position);
Log.d(TAG, "onClick: item"+ position);
startActivity(new Intent(getActivity(), booking.class));
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
@Override
public void onClick(View v) {
onClickListener.onClick(getAdapterPosition());
}
@Override
public void onClick(View v) {
mListener.onClick(getAdapterPosition());
}
按如下所示的方式使用它：
itemView.setOnClickListener(this);
@Override
public void onClick(View v) {
if (v.getId() == id of itemView(R.id.itemview)){
//do not use this
onClickListener.onClick(getAdapterPosition());
//just call the function you need to call on Click of itemview
}
}
希望这有助于
itemView.setOnClickListener（这个）viewholderonClicklistner