Android - Delete item from custom ListView

Question

Does anyone know how to delete an item from a custom ListView? I'm currently working on an Android bar code scanner that stores a scanned item name into an inventory, together with its price. I also want it to be removed when the user clicks on it (but it doesn't works).

This is my code, which might seem messy because I'm still a beginner in Android.

XML:

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="in.aurora.android_barcode_scanner.Inventory"
    android:focusableInTouchMode="false"
    android:clickable="false"
    android:focusable="false">

    <ListView
        android:id="@+id/listView"
        android:layout_width="365dp"
        android:layout_height="495dp"
        tools:layout_editor_absoluteX="10dp"
        tools:layout_editor_absoluteY="8dp"
        android:focusableInTouchMode="false"
        android:clickable="false"
        android:focusable="false"/>
</android.support.constraint.ConstraintLayout>

Implementation:

public void display() {
    ShoppingListAdapter adapter = new ShoppingListAdapter(this,
        R.layout.adapter_view_layout, shoppingList);
    lv = (ListView) findViewById(R.id.listView);

    lv.setAdapter(adapter);
}

@Override
public void onItemClick(AdapterView parent, View view, final int position, long id) {

    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Remove this item?");
    builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            shoppingList.remove(position);

            display();
        }
    });
    builder.setNegativeButton("No", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.cancel();
        }
    });
    builder.show();
}

Adapter:

public class ShoppingListAdapter extends ArrayAdapter<Product> {

    private static final String TAG = "ShoppingListAdapter";

    private Context mContext;
    int mResource;

    public ShoppingListAdapter(Context context, int resource, ArrayList<Product> objects)
    {
        super(context, resource, objects);
        mContext = context;
        mResource = resource;
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, ViewGroup parent)
    {
        String name = getItem(position).getName();
        double price = getItem(position).getPrice();
        String convertPrice = Double.toString(price);

        Product product = new Product(name, price);

        LayoutInflater inflater  = LayoutInflater.from(mContext);
        convertView = inflater.inflate(mResource, parent, false);

        TextView productName = (TextView) 
        convertView.findViewById(R.id.textView1);
        TextView productPrice = (TextView) 
        convertView.findViewById(R.id.textView2);

        productName.setText(name);
        productPrice.setText(convertPrice);

        return convertView;
    }

}

S.R · Accepted Answer · 2017-06-08 16:37:23Z

1

Put this method in your adapter:

public void remove(Product product) {
    objects.remove(product);
    notifyDataSetChanged();
}

Then call it like this:

Product product = shoppingList.get(position);
adapter.remove(product);
adapter.notifyDataSetChanged();

Also make sure your adapter class has getCount and getItem methods:

@Override
public int getCount() {
    if(objects== null){
        return 0;
    }else {
        return objects.isEmpty()? 0 : objects.size();
    }
}


@Override
public Product getItem(int position) {
    return objects.get(position);
}

edited Jun 8, 2017 at 16:37

answered Jun 8, 2017 at 16:25

S.R

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Comments

A.Edwar · Accepted Answer · 2017-06-08 16:28:40Z

0

Make your adapter a field in the activity class

like so :

public class MainActivity extends AppCompatActivity {

    private ShoppingListAdapter mAdapter;

and inside your onCreate method create the shoppingList and the adapter instances And then start adding and removing items from the list and whenever you want to apply your changes in the ListView call mAdapter.notifyDataSetChanged()

like so :

builder.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        shoppingList.remove(position);
        mAdapter.notifyDataSetChanged();
    }
});

answered Jun 8, 2017 at 16:28

A.Edwar

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