Android 应用中的动态 ListView [英] Dynamic ListView in Android app

问题描述

是否有演示如何在 ListView 中动态附加其他行的工作示例?例如:

Is there a working example out there that demonstrates how to append additional rows in ListView dynamically? For example:

1. 您正在从不同的域
2. 然后显示前 10 个项目在 ListView 中(虽然你有中运行的其他线程后台继续拉取提要)
3. 你滚动并到达底部列表并单击一个按钮查看更多项目
4. ListView 然后将被附加附加 10 个项目，其中现在总共制作了 20 件物品.

有什么建议可以做到这一点吗?

Any advice how to accomplish this?

尼古拉斯

推荐答案

要动态地向列表中添加新项目，您必须从 ListActivity 中获取适配器类并简单地添加新元素.当您将项目直接添加到适配器时，将自动为您调用 notifyDataSetChanged - 并且视图会自行更新.

您还可以提供自己的适配器(扩展 ArrayAdapter)并覆盖带 List 参数的构造函数.您可以像使用适配器一样使用此列表，但在这种情况下，您必须自己调用 adapter.notifyDataSetChanged() - 以刷新视图.
请看下面的例子:

To add new item to your list dynamically you have to get adapter class from your ListActivity and simply add new elements. When you add items directly to adapter, notifyDataSetChanged is called automatically for you - and the view updates itself.

You can also provide your own adapter (extending ArrayAdapter) and override the constructor taking List parameter. You can use this list just as you use adapter, but in this case you have to call adapter.notifyDataSetChanged() by yourself - to refresh the view.
Please, take a look at the example below:

public class CustomList extends ListActivity {
private LayoutInflater mInflater;
private Vector<RowData> data;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);        
    mInflater = (LayoutInflater) getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
    data = new Vector<RowData>();
    RowData rd = new RowData("item1", "description1");
    data.add(rd);
    rd = new RowData("item2", "description2");
    data.add(rd);
    rd = new RowData("item2", "description3");
    data.add(rd);

    CustomAdapter adapter = new CustomAdapter(this, R.layout.custom_row,R.id.item, data);
    setListAdapter(adapter);        
    getListView().setTextFilterEnabled(true);
}


public void onListItemClick(ListView parent, View v, int position, long id) {
    CustomAdapter adapter = (CustomAdapter) parent.getAdapter();
    RowData row = adapter.getItem(position);        
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle(row.mItem); 
    builder.setMessage(row.mDescription + " -> " + position );
    builder.setPositiveButton("ok", null);
    builder.show();
}

/**
 * Data type used for custom adapter. Single item of the adapter.      
 */
private class RowData {
    protected String mItem;
    protected String mDescription;

    RowData(String item, String description){
        mItem = item;
        mDescription = description;         
    }

    @Override
    public String toString() {
        return mItem + " " +  mDescription;
    }
}

private class CustomAdapter extends ArrayAdapter<RowData> {

    public CustomAdapter(Context context, int resource,
            int textViewResourceId, List<RowData> objects) {
        super(context, resource, textViewResourceId, objects);

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;

        //widgets displayed by each item in your list
        TextView item = null;
        TextView description = null;

        //data from your adapter
        RowData rowData= getItem(position);


        //we want to reuse already constructed row views...
        if(null == convertView){
            convertView = mInflater.inflate(R.layout.custom_row, null);
            holder = new ViewHolder(convertView);
            convertView.setTag(holder);
        }
        // 
        holder = (ViewHolder) convertView.getTag();
        item = holder.getItem();
        item.setText(rowData.mItem);

        description = holder.getDescription();      
        description.setText(rowData.mDescription);

        return convertView;
    }
}

/**
 * Wrapper for row data.
 *
 */
private class ViewHolder {      
    private View mRow;
    private TextView description = null;
    private TextView item = null;

    public ViewHolder(View row) {
        mRow = row;
    }

    public TextView getDescription() {
        if(null == description){
            description = (TextView) mRow.findViewById(R.id.description);
        }
        return description;
    }

    public TextView getItem() {
        if(null == item){
            item = (TextView) mRow.findViewById(R.id.item);
        }
        return item;
    }       
}

}

您可以扩展上面的示例并添加更多"按钮 - 这只是将新项目添加到您的适配器(或矢量).
问候！

You can extend the example above and add "more" button - which just add new items to your adapter (or vector).
Regards!

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