我的ListFragment代码
public class ItemFragment extends ListFragment {
private DatabaseHandler dbHelper;
private static final String TITLE = "Items";
private static final String LOG_TAG = "debugger";
private ItemAdapter adapter;
private List<Item> items;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.item_fragment_list, container, false);
return view;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.setHasOptionsMenu(true);
super.onCreate(savedInstanceState);
getActivity().setTitle(TITLE);
dbHelper = new DatabaseHandler(getActivity());
items = dbHelper.getItems();
adapter = new ItemAdapter(getActivity().getApplicationContext(), items);
this.setListAdapter(adapter);
}
@Override
public void onResume() {
super.onResume();
items.clear();
items = dbHelper.getItems(); //reload the items from database
adapter.notifyDataSetChanged();
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
if(dbHelper != null) { //item is edited
Item item = (Item) this.getListAdapter().getItem(position);
Intent intent = new Intent(getActivity(), AddItemActivity.class);
intent.putExtra(IntentConstants.ITEM, item);
startActivity(intent);
}
}
}
我的ListView
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
但这不会刷新ListView
。即使在重启应用程序后,更新的项目也不会显示。我的ItemAdapter
扩展了BaseAdapter
public class ItemAdapter extends BaseAdapter{
private LayoutInflater inflater;
private List<Item> items;
private Context context;
public ProjectListItemAdapter(Context context, List<Item> items) {
super();
inflater = LayoutInflater.from(context);
this.context = context;
this.items = items;
}
@Override
public int getCount() {
return items.size();
}
@Override
public Object getItem(int position) {
return items.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ItemViewHolder holder = null;
if(convertView == null) {
holder = new ItemViewHolder();
convertView = inflater.inflate(R.layout.list_item, parent,false);
holder.itemName = (TextView) convertView.findViewById(R.id.topText);
holder.itemLocation = (TextView) convertView.findViewById(R.id.bottomText);
convertView.setTag(holder);
} else {
holder = (ItemViewHolder) convertView.getTag();
}
holder.itemName.setText("Name: " + items.get(position).getName());
holder.itemLocation.setText("Location: " + items.get(position).getLocation());
if(position % 2 == 0) {
convertView.setBackgroundColor(context.getResources().getColor(R.color.evenRowColor));
} else {
convertView.setBackgroundColor(context.getResources().getColor(R.color.oddRowColor));
}
return convertView;
}
private static class ItemViewHolder {
TextView itemName;
TextView itemLocation;
}
}
有人能帮帮忙吗?
发布于 2013-02-03 09:52:54
在ItemFragment
中查看onResume
方法
@Override
public void onResume() {
super.onResume();
items.clear();
items = dbHelper.getItems(); // reload the items from database
adapter.notifyDataSetChanged();
}
在调用notifyDataSetChanged()
之前,您刚刚更新的不是适配器的字段private List<Item> items;
,而是片段中声明相同的字段。适配器仍然存储对您创建适配器时传递的项目列表的引用(例如,在片段的onCreate中)。让你的代码像你所期望的那样运行的最短的(就改变次数而言)但不是很优雅的方法是简单地替换行:
items = dbHelper.getItems(); // reload the items from database
使用
items.addAll(dbHelper.getItems()); // reload the items from database
一个更优雅的解决方案:
1)从ItemFragment
中删除items private List<Item> items;
-我们只需要在适配器中保留对它们的引用
2)将onCreate修改为:
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
super.setHasOptionsMenu(true);
getActivity().setTitle(TITLE);
dbHelper = new DatabaseHandler(getActivity());
adapter = new ItemAdapter(getActivity(), dbHelper.getItems());
setListAdapter(adapter);
}
3)在ItemAdapter中添加方法:
public void swapItems(List<Item> items) {
this.items = items;
notifyDataSetChanged();
}
4)将您的onResume更改为:
@Override
public void onResume() {
super.onResume();
adapter.swapItems(dbHelper.getItems());
}
发布于 2013-01-30 21:46:09
您正在将重新加载的项分配给onResume()
中的全局变量项,但这不会反映在ItemAdapter
类中,因为它有自己的名为“items”的实例变量。
为了刷新刷新,在ItemAdapter
类中添加一个ListView
(),它接受列表数据,即条目
class ItemAdapter
{
.....
public void refresh(List<Item> items)
{
this.items = items;
notifyDataSetChanged();
}
}
使用以下代码更新onResume()
@Override
public void onResume()
{
super.onResume();
items.clear();
items = dbHelper.getItems(); //reload the items from database
**adapter.refresh(items);**
}
发布于 2013-02-02 04:20:24
在onResume()中更改此行
items = dbHelper.getItems(); //reload the items from database
至
items.addAll(dbHelper.getItems()); //reload the items from database
问题是你从来没有告诉你的适配器关于新的项目列表。如果您不想将新列表传递给适配器(看起来您并不想),那么只需在clear()
之后使用items.addAll
即可。这将确保您修改的列表与适配器引用的列表相同。
https://stackoverflow.com/questions/14503006
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