是否有一个可行的示例来演示如何在 ListView 中动态附加额外的行? 例如:
- 您正在从 不同的域
- 然后显示前 10 个项目 在 ListView 中(当你有 中运行的其他线程 后台继续拉提要)
- 您滚动并到达底部 列表并单击一个按钮以 查看更多项目
- ListView 然后将被附加 加上额外的 10 项,其中 现在总共生产 20 件商品。
任何建议如何做到这一点?
尼古拉斯
最佳答案
要动态地将新项目添加到列表中,您必须从 ListActivity 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,会自动为您调用 notifyDataSetChanged - 并且 View 会自行更新。
您还可以提供自己的适配器(扩展 ArrayAdapter)并覆盖带有 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 View 。
请看下面的例子:
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 vector )。
问候!
关于java - Android 应用中的动态 ListView,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/1917773/