Android ArrayAdapter：如何从适配器内删除项目

Question

In my App I have two lists of vehicles: full list and my favorites. When In favorites I show the option for the user to delete the vehicle from this favorites:

To show this custom listview item I implemented the following adapter:

public class VehicleAdapter extends ArrayAdapter<Vehicle> {


    private int listType=1;

    public Vehicle[] vehicles;

    public VehicleAdapter(@NonNull Context context, @LayoutRes int resource, @NonNull Vehicle[] objects, int listType) {
        super(context, resource, objects);
        this.listType = listType;
        this.vehicles = objects;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        LayoutInflater layoutInflater = LayoutInflater.from(getContext());
        View customView = layoutInflater.inflate(R.layout.vehicle_row, null);

        Vehicle vehicle = getItem(position);

        ImageView imgVehicle = (ImageView) customView.findViewById(R.id.imgVehicle);
        TextView txtTitle = (TextView) customView.findViewById(R.id.txtTitle);
        TextView txtDescription = (TextView) customView.findViewById(R.id.txtDescription);

        txtTitle.setText(vehicle.name);
        txtDescription.setText(vehicle.short_description);
        Picasso.with(getContext()).load(vehicle.picture).into(imgVehicle);

        // If it's the favorites list
        if(listType == 2) {
            Button btnDelete = (Button) customView.findViewById(R.id.btnDelete);
            btnDelete.setVisibility(View.VISIBLE);

            final int itemPosition = position;
            btnDelete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    Vehicle item = VehicleAdapter.this.vehicles[itemPosition];
                    remove(item); // HERE: throws fatal error
                    notifyDataSetChanged();
                }
            });
        }

        return customView;
    }
}

How I instantiate the adapter in the fragment (I'm loading the list inside a fragment):

Vehicle[] items = new Vehicle[vehicles.size()];
items = vehicles.toArray(items);

ListAdapter vehicleAdapter = new VehicleAdapter(getActivity(), R.layout.vehicle_row, items, mListType);

final ListView listView = (ListView) getView().findViewById(R.id.listView);
listView.setAdapter(vehicleAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
        Vehicle vehicle = (Vehicle) adapterView.getItemAtPosition(i);
        ((MainActivity)getActivity()).loadVehicleInformation(vehicle);
    }
});

The exception:

Exception java.lang.UnsupportedOperationException:
java.util.AbstractList.remove (AbstractList.java:638)
java.util.AbstractList$SimpleListIterator.remove (AbstractList.java:75)
java.util.AbstractCollection.remove (AbstractCollection.java:229)
android.widget.ArrayAdapter.remove (ArrayAdapter.java:244)
xx.xx.xxxxxx.VehicleAdapter.remove (VehicleAdapter.java:78)
xx.xx.xxxx.VehicleAdapter$1.onClick (VehicleAdapter.java:62)
android.view.View.performClick (View.java:4756)
android.view.View$PerformClick.run (View.java:19749)
android.os.Handler.handleCallback (Handler.java:739)
android.os.Handler.dispatchMessage (Handler.java:95)
android.os.Looper.loop (Looper.java:135)
android.app.ActivityThread.main (ActivityThread.java:5221)

My problem: I'm not sure if I'm using the right approach with the delete button. As you can see I add a listener to it in the adapter class. I can get the right item but when I try to remove it throws a fatal error. I believe I'm using the wrong approach but I'm lost on how I could do this delete option.

Thanks for any help

Answer 1

Instead of sending, Verhicle[] send as ArrayList, if we send as an array it can't be modified in ArrayAdapter.

public class VehicleAdapter extends ArrayAdapter<Vehicle> {

    private int listType=1;

    public ArrayList<Vehicle> vehicles;

    public VehicleAdapter(@NonNull Context context, @LayoutRes int resource, @NonNull ArrayList<Vehicle> objects, int listType) {
        super(context, resource, objects);
        this.listType = listType;
        this.vehicles = objects;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        LayoutInflater layoutInflater = LayoutInflater.from(getContext());
        View customView = layoutInflater.inflate(R.layout.vehicle_row, null);

        final Vehicle vehicle = getItem(position);

        ImageView imgVehicle = (ImageView) customView.findViewById(R.id.imgVehicle);
        TextView txtTitle = (TextView) customView.findViewById(R.id.txtTitle);
        TextView txtDescription = (TextView) customView.findViewById(R.id.txtDescription);

        txtTitle.setText(vehicle.name);
        txtDescription.setText(vehicle.short_description);
        Picasso.with(getContext()).load(vehicle.picture).into(imgVehicle);

        // If it's the favorites list
        if(listType == 2) {
            Button btnDelete = (Button) customView.findViewById(R.id.btnDelete);
            btnDelete.setVisibility(View.VISIBLE);

            btnDelete.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    remove(vehicle);
                    notifyDataSetChanged();
                }
            });
        }

        return customView;
    }
}