Android ListView条目内增减按钮修改对应商品数量实现方法咨询

要实现ListView条目内增减按钮修改对应数量，只需要按以下步骤调整即可，核心逻辑是给数据源新增数量存储字段，自定义Adapter绑定按钮点击事件：

1. 调整数据源，新增商品数量字段 #

原有代码中HashMap只存储了商品名、价格、图片，需要新增count字段存储每个商品的购买数量，修改加载JSON的循环逻辑：

try {
    JSONObject obj=new JSONObject(LoadFromJsonAssets());
    Resources resources = context.getResources();
    JSONArray array =obj.getJSONArray("domestic");
    HashMap<String,String> list;
    ArrayList<HashMap<String,String>> arrayList=new ArrayList<>();
    for (int i=0;i<array.length();i++){
        JSONObject o=array.getJSONObject(i);
        String productName=o.getString("productName");
        String productPrice=o.getString("productPrice");
        String productPic=o.getString("productPic");

        final int resourceId = resources.getIdentifier(productPic, "drawable", context.getPackageName());
        list= new HashMap<>();
        list.put("productName",productName);
        list.put("productPrice",productPrice);
        list.put("productPic",Integer.toString(resourceId) );
        // 新增数量字段，默认0
        list.put("count", "0");
        arrayList.add(list);
    }
    // 这里替换为自定义Adapter，后面会给出实现
    final CustomListAdapter adapter = new CustomListAdapter(this, arrayList);
    listView.setAdapter(adapter);
} catch (Exception e) {
    e.printStackTrace();
}

2. 自定义ListView适配类，绑定按钮点击事件 #

新建CustomListAdapter.java文件，继承BaseAdapter，在getView方法中绑定每个条目的增减按钮点击事件，修改对应位置的数量后刷新列表：

public class CustomListAdapter extends BaseAdapter {
    private Context context;
    private ArrayList<HashMap<String, String>> dataList;

    public CustomListAdapter(Context context, ArrayList<HashMap<String, String>> dataList) {
        this.context = context;
        this.dataList = dataList;
    }

    @Override
    public int getCount() {
        return dataList.size();
    }

    @Override
    public Object getItem(int position) {
        return dataList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder;
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.list_view_design, parent, false);
            holder = new ViewHolder();
            holder.productPic = convertView.findViewById(R.id.productPic);
            holder.productName = convertView.findViewById(R.id.productName);
            holder.productPrice = convertView.findViewById(R.id.productPrice);
            holder.decreaseBtn = convertView.findViewById(R.id.decreasing);
            holder.countTv = convertView.findViewById(R.id.counterrrr);
            holder.increaseBtn = convertView.findViewById(R.id.Increasing);
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder) convertView.getTag();
        }

        HashMap<String, String> item = dataList.get(position);
        holder.productName.setText(item.get("productName"));
        holder.productPrice.setText(item.get("productPrice"));
        holder.productPic.setImageResource(Integer.parseInt(item.get("productPic")));
        holder.countTv.setText(item.get("count"));

        // 给按钮设置当前位置tag，避免列表复用时点击事件错位
        holder.increaseBtn.setTag(position);
        holder.decreaseBtn.setTag(position);

        // 增加按钮点击事件
        holder.increaseBtn.setOnClickListener(v -> {
            int pos = (int) v.getTag();
            HashMap<String, String> curItem = dataList.get(pos);
            int count = Integer.parseInt(curItem.get("count"));
            count++;
            curItem.put("count", String.valueOf(count));
            notifyDataSetChanged();
        });

        // 减少按钮点击事件
        holder.decreaseBtn.setOnClickListener(v -> {
            int pos = (int) v.getTag();
            HashMap<String, String> curItem = dataList.get(pos);
            int count = Integer.parseInt(curItem.get("count"));
            if (count > 0) {
                count--;
                curItem.put("count", String.valueOf(count));
                notifyDataSetChanged();
            }
        });

        return convertView;
    }

    // 缓存控件，避免重复执行findViewById提升性能
    static class ViewHolder {
        ImageView productPic;
        TextView productName;
        TextView productPrice;
        ImageView decreaseBtn;
        TextView countTv;
        ImageView increaseBtn;
    }
}

3. 效果参考 #

内容的提问来源于stack exchange，提问作者Muratcan Yıldız