在我的应用程序中，listview 是从 SQLite 数据库加载的，它使用 SimpleAdapter 来设置 ListView。当用户在 listitem 上执行 longclick 时，该项目将从数据库中删除，它应该更新 listviw。但是当我从数据库中删除项目时，listview 会同时显示旧数据和新数据。请提出一些解决方案。谢谢。
以下是我的代码：
public class FavouriteListActivity extends ListActivity {
public final ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
ListAdapter adapter;
public ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();
ArrayList<String> titles = new ArrayList<String>();
String title,artist;
SQLiteAdapter adp;
SimpleCursorAdapter cursoradp;
Cursor cursor,cursorDB;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.favouritelist);
// Adding menuItems to ListView
final String[] from = {"songTitle", "artist","duration"};
final int[] to={R.id.fav_songTitle,R.id.fav_songArtist,R.id.fav_duration};
ListView lv = getListView();
songsListData = getFavourites();
final ListAdapter adapter = new SimpleAdapter(this,songsListData,
R.layout.favouritelist_item, from, to);
lv.setFastScrollEnabled(true);
setListAdapter(adapter);
lv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener()
{
public boolean onItemLongClick(AdapterView<?> av, View v,
final int pos,final long id) {
final AlertDialog.Builder b = new AlertDialog.Builder(FavouriteListActivity.this);
b.setTitle("Are you sure you want to delete?");
b.setIcon(android.R.drawable.ic_delete);
b.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
String title = songsListData.get(pos).get("songTitle");
ListAdapter adapter = null;
adp.delete_byTitle(title);
songsListData.clear();
setListAdapter(null);
songsListData = getFavourites();
adapter = new SimpleAdapter(getApplicationContext(), songsListData,R.layout.favouritelist_item, from, to);
setListAdapter(adapter);
Toast.makeText(FavouriteListActivity.this,"Song is removed from Favourites", Toast.LENGTH_SHORT).show();
}
});
b.setNegativeButton("No", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
dialog.cancel();
}
});
b.show();
return true;
}
});
}
public ArrayList<HashMap<String,String>> getFavourites()
{
ArrayList<HashMap<String, String>> songsListData = new ArrayList<HashMap<String, String>>();
ArrayList<String> titles = new ArrayList<String>();
adp = new SQLiteAdapter(this);
adp.openToRead();
cursorDB = adp.queueAll();
if(cursorDB.moveToFirst())
{
for(int i=0;i<cursorDB.getCount();i++)
{
titles.add(cursorDB.getString(cursorDB.getColumnIndex("Title")));
cursorDB.moveToNext();
}
String[] songTitles = new String[titles.size()];
songTitles = titles.toArray(songTitles);
if(songTitles == null)
{
songTitles =null;
}
String whereClause = MediaStore.Audio.Media.TITLE + " IN ( ?";
if (songTitles.length>1)
{
for (int j = 1 ; j < songTitles.length; ++j)
{
whereClause+=", ?";
}
}
whereClause+=")";
Cursor cursor = managedQuery(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null ,whereClause,songTitles,MediaStore.Audio.Media.TITLE);
if (cursor == null)
{
//Query Failed , Handle error.
}
else if (!cursor.moveToFirst())
{
//No media on the device.
}
else
{
int titleColumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media.TITLE);
int idColumn = cursor.getColumnIndexOrThrow(android.provider.MediaStore.Audio.Media.DATA);
int artistcolumn = cursor.getColumnIndex(android.provider.MediaStore.Audio.Media.ARTIST);
int durationcolumn =cursor.getColumnIndex(android.provider.MediaStore.Audio.Media.DURATION);
for(int i=0;i<cursor.getCount();i++)
{
String thisTitle = cursor.getString(titleColumn);
String path = cursor.getString(idColumn);
String artist = cursor.getString(artistcolumn);
Long duration = cursor.getLong(durationcolumn);
Utilities objUtilities = new Utilities();
String timeDuration = objUtilities.milliSecondsToTimer(duration);
HashMap<String, String> song = new HashMap<String, String>();
song.put("songTitle",thisTitle);
song.put("songPath", path);
song.put("artist", artist);
song.put("duration",timeDuration);
// Adding each song to SongList
songsList.add(song);
cursor.moveToNext();
}
}
// looping through playlist
for (int i = 0; i < songsList.size(); i++) {
// creating new HashMap
HashMap<String, String> song = songsList.get(i);
// adding HashList to ArrayList
songsListData.add(song);
}
}
return songsListData;
}
}