当显示用户对话框以使用用户并长时间按下时，我试图删除 ListView 中以及数据库中的一行。
我尝试过以下代码:
Place.java(对于模型 - getter 和 setter 方法)
public class Place {
int _id;
private String mname;
private double mlatitude,mlongitude;
private String mplacedetails;
public Place(int id, String name, double latitude, double longitude,String placedetails)
{
this._id = id;
mname = name;
mlatitude = latitude;
mlongitude = longitude;
mplacedetails = placedetails;
}
public Place(String name, double latitude, double longitude,String placedetails)
{
mname = name;
mlatitude = latitude;
mlongitude = longitude;
mplacedetails = placedetails;
}
public Place() {
}
public int getID(){
return this._id;
}
public void setID(int id){
this._id = id;
}
public void setname(String placename)
{
mname = placename;
}
public String getname()
{
return mname;
}
public void setlatitude(double latitude)
{
mlatitude=latitude;
}
public double getlatitude()
{
return mlatitude;
}
public void setlongitude(double longitude)
{
mlongitude = longitude;
}
public double getlongitude()
{
return mlongitude;
}
public void setPlacedetails(String placedetails)
{
mplacedetails = placedetails;
}
public String getplacedetails()
{
return mplacedetails;
}
}
PlaceAdapter.java - 用于 ListView listview_places
public class PlacesAdapter extends ArrayAdapter<Place>{
Context mcontext;
int mlayoutResourceId;
List<Place> mdata = null;
View row;
public PlacesAdapter(Context context, int layoutResourceId, List<Place> data) {
super(context, layoutResourceId, data);
mlayoutResourceId = layoutResourceId;
mcontext = context;
mdata = data;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
row = convertView;
PlaceHolder holder = null;
if(row == null)
{
LayoutInflater inflater = ( (Activity) mcontext).getLayoutInflater();
row = inflater.inflate(mlayoutResourceId, parent, false);
holder = new PlaceHolder(row);
row.setTag(holder);
Log.d("my","new row is inflated for listview current position");
}
else
{
holder = (PlaceHolder)row.getTag();
Log.d("my","row is taken from the holder");
}
Place p = mdata.get(position);
holder.txt_place_title.setText(p.getname());
holder.txt_place_details.setText(p.getplacedetails());
return row;
}
class PlaceHolder
{
TextView txt_place_title;
TextView txt_place_details;
public PlaceHolder(View v){
txt_place_title = (TextView)row.findViewById(R.id.txt_Place_Title);
txt_place_details = (TextView)row.findViewById(R.id.txt_Place_Details);
}
}
}
MySQLiteHelper.java - 用于数据库 Controller
public class MySqliteHelper extends SQLiteOpenHelper{
private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "MyApplicationDatabase";
private static final String KEY_ID = "id";
private static final String KEY_PLACENAME = "placename";
private static final String KEY_PLACEDETAILS = "placedetails";
private static final String KEY_LATITUDE = "latitude";
private static final String KEY_LONGITUDE = "longitude";
private static final String TABLE_NAME = "places";
public MySqliteHelper(Context context) {
super(context, DATABASE_NAME,null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
//actual query = create table places (id primary key autoincrement, placename taxt, latitude real, longitude real);
String query = "CREATE TABLE " +TABLE_NAME + "( " + KEY_ID+
" INTEGER PRIMARY KEY, " + KEY_PLACENAME+
" TEXT, "+ KEY_PLACEDETAILS+
" TEXT, "+ KEY_LATITUDE+
" REAL, "+KEY_LONGITUDE+ " REAL)";
db.execSQL(query);
Log.d("my", "Successfully created table: " + query);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS places");
this.onCreate(db);
}
public void addPlaces(Place place)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues convalues = new ContentValues();
convalues.put(KEY_PLACENAME,place.getname());
convalues.put(KEY_LATITUDE,place.getlatitude());
convalues.put(KEY_LONGITUDE,place.getlongitude());
convalues.put(KEY_PLACEDETAILS,place.getplacedetails());
db.insert(TABLE_NAME, null, convalues);
Log.d("my","db.insert(TABLE_NAME, null, convalues)");
Log.d("my", "Values inserted");
db.close();
}
public Place getPlace(int id) {
Place place = null;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_NAME, new String[]{KEY_ID, KEY_LATITUDE, KEY_LONGITUDE,
KEY_PLACENAME, KEY_PLACEDETAILS}, KEY_ID + "=?",
new String[]{String.valueOf(id)}, null, null, null, null);
if (cursor != null) {
cursor.moveToFirst();
}
place = new Place(cursor.getInt(cursor.getColumnIndex("_ID")), cursor.getString(cursor.getColumnIndex(KEY_PLACENAME)),
cursor.getDouble(cursor.getColumnIndex(KEY_LATITUDE)), cursor.getDouble(cursor.getColumnIndex(KEY_LONGITUDE)), cursor.getString(cursor.getColumnIndex(KEY_PLACEDETAILS)));
cursor.close();
db.close();
return place;
}
public List<Place> getAllPlaces() {
List<Place> placeList = new ArrayList<Place>();
SQLiteDatabase db = this.getWritableDatabase();
String selectQuery = "SELECT * FROM " + TABLE_NAME;
Cursor cursor = db.rawQuery(selectQuery, null);
Log.d("my","query fired");
Log.d("my",cursor.toString());
if (cursor.moveToFirst()) {
Log.d("my","in movetofirst()");
do {
Log.d("my","in do");
Place place = new Place();
place.setname(cursor.getString(cursor.getColumnIndex(KEY_PLACENAME)));
place.setlatitude(cursor.getDouble(cursor.getColumnIndex(KEY_LATITUDE)));
place.setlongitude(cursor.getDouble(cursor.getColumnIndex(KEY_LONGITUDE)));
place.setPlacedetails(cursor.getString(cursor.getColumnIndex(KEY_PLACEDETAILS)));
placeList.add(place);
} while (cursor.moveToNext());
}
return placeList;
}
public void deletePlaces(Place place)
{
SQLiteDatabase db = this.getWritableDatabase();
db.delete(TABLE_NAME, KEY_ID + " = ?",
new String[] { String.valueOf(place.getID()) });
db.close();
}
public int updatePlaces(Place place) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KEY_PLACENAME, place.getname());
values.put(KEY_PLACEDETAILS, place.getplacedetails());
return db.update(TABLE_NAME, values, KEY_ID + " = ?",
new String[] { String.valueOf(place.getID()) });
}
public void deleteByName(String name) {
SQLiteDatabase db= this.getWritableDatabase();
db.delete(TABLE_NAME, KEY_PLACENAME +"=?", new String [] { name });
db.close();
}
}
和 ShowPlaces.java Activity 具有名为 PlaceholderFragment.java 的 fragment : - 其中适配器设置为 listview_places 并且对话框显示在 itemlongclick 上.
public class PlaceholderFragment extends Fragment {
public ListView listview_places;
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_show_place, container, false);
MySqliteHelper db = new MySqliteHelper(getActivity().getBaseContext());
List<Place> places = db.getAllPlaces();
for (Place p : places){
String log = "name:" +p.getname() + " ,details: " + p.getplacedetails();
Log.d("my", log);
}
listview_places = (ListView)rootView.findViewById(R.id.listView_places);
final PlacesAdapter places_adapter = new PlacesAdapter(getActivity(),R.layout.listview_item_row,places);
Log.d("my", "adapter constructor is working");
listview_places.setAdapter(places_adapter);
listview_places.setLongClickable(true);
listview_places.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
public boolean onItemLongClick(AdapterView<?> parent, View view,
final int pos, long id) {
new AlertDialog.Builder(getActivity())
.setTitle("Delete Place")
.setMessage("Are you sure you want to delete this place?")
.setPositiveButton("Delete", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
}
})
.setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
// do nothing
}
})
.setIcon(android.R.drawable.ic_menu_delete)
.show();
return true;
}
});
db.close();
return rootView;
}
}
我想要做的是，当用户单击 DialougeBox 中的删除按钮时，删除 listview_places 以及数据库中的行。
对于数据库，如您所见，MySQLiteHelper.java 中已经有一个名为 deleteByName() 的方法。
所以，我认为看起来也更复杂......我可以说我想做的是调用 MySQLiteHelpder 和 的 之间的 ListView deleteByName 方法>removelist_view_places 方法
.setPositiveButton("Delete", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
//I want to delete place from listview and database here.
}
})
我已经尝试过很多次了:
nameArray.remove(position);
// dh.Deleteitem();
adapter.notifyDataSetChanged();
adapter=new ListAdapter(getActivity(), nameArray);
list.setAdapter(adapter);
但是..有时它无法显示如果从内部类访问适配器应该是最终的。如果我将适配器设置为final，则显示notifyDatasetChanged 无法解析。
我应该做什么？
最佳答案
现在我解决了!
工作了几个小时后，我找到了解决方案:
在我的 ListView onItemClickListener内，然后在对话框的肯定按钮onclick内，我使用了，
Place place = places_adapter.getItem(pos);
places_adapter.remove(place);
db.deletePlaces(place);
places_adapter.notifyDataSetChanged();
您只需从适配器中删除。适配器充当 Controller 。最后不要忘记notifyDataSetChanged()。
完整代码:
listview_places.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
new AlertDialog.Builder(getActivity())
.setTitle("Delete Place")
.setMessage("Are you sure you want to delete this place?")
.setPositiveButton("Delete", new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int which) {
Place place = places_adapter.getItem(pos);
places_adapter.remove(place);
db.deletePlaces(place);
places_adapter.notifyDataSetChanged();
}
})
});
关于java - 单击对话框按钮时从 ListView 中删除行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/27584465/