Question

有谁知道如何从自定义ListView中删除项目？我目前正在开发一种Android条形码扫描仪，它将扫描的商品名称及其价格存储在库存中。我还希望在用户点击它时将其删除（但它不起作用）。

这是我的代码，可能看起来很乱，因为我还是Android的初学者。

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>

实现：

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();
}

适配器：

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;
    }

}

Answer 1

将此方法放在适配器中：

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

然后这样称呼：

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

还要确保您的adapter课程有getCount和getItem方法：

@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);
}

Answer 2

使适配器成为活动类

中的字段像这样：

public class MainActivity extends AppCompatActivity {

    private ShoppingListAdapter mAdapter;

并在onCreate方法中创建shoppingList和适配器实例然后开始在列表中添加和删除项目，以及在ListView调用mAdapter.notifyDataSetChanged()

中应用更改的时间像这样：

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

Android - 从自定义ListView中删除项目

XML：

实现：

适配器：

2 个答案: