android - 通过 onClickListener 在自定义适配器中按位置获取数据

Question

查看我的扩展 BaseAdapter 的自定义适配器:

public class DrawerAdapter extends BaseAdapter{

    static class ViewHolder{
        TextView        cat_Title;
        TextView        cat_Count;
    }

    private Activity                            mActivity;
    private ArrayList<HashMap<String, String>>  mData;
    private static LayoutInflater               mInflater;
    private JsonArray Categories                = null;
    public JsonObject Cat_Items                 = null;

    private static String                       CATEGORY_NAME;
    private static String                       CATEGORY_CNT;
    private static String                       CATEGORY_ID;

    public DrawerAdapter(Activity a, ArrayList<HashMap<String, String>> d){
        mActivity   = a;
        mData       = d;
        mInflater   = (LayoutInflater) mActivity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

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

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

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

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

        View dView              = convertView;
        ViewHolder holder       = null;

        HashMap<String, String> dCategorise = new HashMap<String, String>();
        dCategorise             = mData.get(position);
        CATEGORY_NAME           = dCategorise.get("CATEGORY_NAME");
        CATEGORY_CNT            = dCategorise.get("CATEGORY_CNT");
        CATEGORY_ID             = dCategorise.get("CATEGORY_ID");


        if (convertView == null){
            dView               = mInflater.inflate(R.layout.layout_drawer_list_row, null);
            holder              = new ViewHolder();

            holder.cat_Title    = (TextView) dView.findViewById(R.id.category_title);
            holder.cat_Count    = (TextView) dView.findViewById(R.id.category_counter);

            dView.setTag(holder);

        }else{
            holder = (ViewHolder) dView.getTag();
        }


        holder.cat_Title.setTag(position);
        holder.cat_Title.setTypeface(MyriadRegular);
        holder.cat_Title.setText(CATEGORY_NAME);

        holder.cat_Count.setTypeface(Yagut);
        holder.cat_Count.setText(CATEGORY_CNT);


        holder.cat_Title.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                int pos         = (Integer) v.getTag();
                String cat_ID   = mData.get(pos).get(CATEGORY_ID);
            }
        });
        return dView;
    }

}

这是我的自定义适配器，我在我的抽屉导航中使用它。我想通过单击类别标题获取类别 ID 并将其发送到 fragment 并基于此更改 fragment 数据库。但是对于 cat_ID 返回 null

现在我的问题:1.为什么返回null？2.获取发送到fragment的category id的方式是否正确？

Answer 1

我建议在您从 HashMap 中获取 CATEGORY_ID 时直接将其添加到按钮的标签中

示例:

改变这个:

holder.cat_Title.setTag(position);

到:

holder.cat_Title.setTag(CATEGORY_ID);
public void onClick(View v) {
            String cat_ID        = (String) v.getTag();
        }