我创建了一个应用程序，允许用户通过地方选择器添加位置并将它们添加到SQLite数据库中。我在recyclerview中显示这些位置。为了从recyclerview中删除一个项目，这是我到目前为止所做的。
1）用户长时间按下recyclerview中的项目，然后出现警告对话框，其中包含2个按钮（删除和取消）。
我能做什么：
1）现在，当用户点击删除按钮时，我不知道如何从recyclerview和SQLite数据库中删除项目。
我已经搜索过了，但不知道如何实施。我发布了MainActivity.java类，PlaceDbhelper.java类和PlacelistAdapter.java类的代码。
MainActivity.java类
public class MainActivity extends AppCompatActivity implements
ConnectionCallbacks,
OnConnectionFailedListener {
// Constants
public static final String TAG = MainActivity.class.getSimpleName();
private static final int PERMISSIONS_REQUEST_FINE_LOCATION = 111;
private static final int PLACE_PICKER_REQUEST = 1;
// Member variables
private PlaceListAdapter mAdapter;
private RecyclerView mRecyclerView;
private boolean mIsEnabled;
private GoogleApiClient mClient;
private Geofencing mGeofencing;
//String arr;
/**
* Called when the activity is starting
*
* @param savedInstanceState The Bundle that contains the data supplied in onSaveInstanceState
*/
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Set up the recycler view
mRecyclerView = (RecyclerView) findViewById(R.id.places_list_recycler_view);
mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
mAdapter = new PlaceListAdapter(this, null);
mRecyclerView=(RecyclerView)findViewById(R.id.places_list_recycler_view);
mRecyclerView.setAdapter(mAdapter);
Switch onOffSwitch = (Switch) findViewById(R.id.enable_switch);
mIsEnabled = getPreferences(MODE_PRIVATE).getBoolean(getString(R.string.setting_enabled), false);
onOffSwitch.setChecked(mIsEnabled);
onOffSwitch.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
SharedPreferences.Editor editor = getPreferences(MODE_PRIVATE).edit();
editor.putBoolean(getString(R.string.setting_enabled), isChecked);
mIsEnabled = isChecked;
editor.commit();
if (isChecked) mGeofencing.registerAllGeofences();
else mGeofencing.unRegisterAllGeofences();
}
});
mClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.addApi(Places.GEO_DATA_API)
.enableAutoManage(this, this)
.build();
mGeofencing = new Geofencing(this, mClient);
mRecyclerView.addOnItemTouchListener(new RecyclerTouchListener(this,
mRecyclerView, new ClickListener() {
public void onClick(View view, final int position) {
picture.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
}
});*/
}
public void onItemClick(View view, int position) {
}
@Override
public void onLongClick(View view, int position) {
final AlertDialog alertDialog =new AlertDialog.Builder(MainActivity.this).create();
alertDialog.setTitle("Are you want to delete this");
alertDialog.setCancelable(false);
alertDialog.setMessage("By deleting this, item will permanently be deleted. Are you still want to delete this?");
alertDialog.setButton(DialogInterface.BUTTON_POSITIVE, "Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
alertDialog.setButton(DialogInterface.BUTTON_NEGATIVE, "Delete", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
alertDialog.show();
Toast.makeText(MainActivity.this, "Long press on position :"+position,
Toast.LENGTH_LONG).show();
}
}));
}
/***
* Called when the Google API Client is successfully connected
*
* @param connectionHint Bundle of data provided to clients by Google Play services
*/
@Override
public void onConnected(@Nullable Bundle connectionHint) {
refreshPlacesData();
Log.i(TAG, "API Client Connection Successful!");
}
/***
* Called when the Google API Client is suspended
*
* @param cause cause The reason for the disconnection. Defined by constants CAUSE_*.
*/
@Override
public void onConnectionSuspended(int cause) {
Log.i(TAG, "API Client Connection Suspended!");
}
/***
* Called when the Google API Client failed to connect to Google Play Services
*
* @param result A ConnectionResult that can be used for resolving the error
*/
@Override
public void onConnectionFailed(@NonNull ConnectionResult result) {
Log.e(TAG, "API Client Connection Failed!");
}
public void refreshPlacesData() {
Uri uri = PlaceContract.PlaceEntry.CONTENT_URI;
Cursor data = getContentResolver().query(
uri,
null,
null,
null,
null);
if (data == null || data.getCount() == 0) return;
List<String> guids = new ArrayList<String>();
while (data.moveToNext()) {
guids.add(data.getString(data.getColumnIndex(PlaceContract.PlaceEntry.COLUMN_PLACE_ID)));
}
PendingResult<PlaceBuffer> placeResult = Places.GeoDataApi.getPlaceById(mClient,
guids.toArray(new String[guids.size()]));
placeResult.setResultCallback(new ResultCallback<PlaceBuffer>() {
@Override
public void onResult(@NonNull PlaceBuffer places) {
mAdapter.swapPlaces(places);
mGeofencing.updateGeofencesList(places);
if (mIsEnabled) mGeofencing.registerAllGeofences();
}
});
}
public void onAddPlaceButtonClicked(View view) {
if (ActivityCompat.checkSelfPermission(this, android.Manifest.permission.ACCESS_FINE_LOCATION)
!= PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, getString(R.string.need_location_permission_message), Toast.LENGTH_LONG).show();
return;
}
try {
PlacePicker.IntentBuilder builder = new PlacePicker.IntentBuilder();
Intent i = builder.build(this);
startActivityForResult(i, PLACE_PICKER_REQUEST);
} catch (GooglePlayServicesRepairableException e) {
Log.e(TAG, String.format("GooglePlayServices Not Available [%s]", e.getMessage()));
} catch (GooglePlayServicesNotAvailableException e) {
Log.e(TAG, String.format("GooglePlayServices Not Available [%s]", e.getMessage()));
} catch (Exception e) {
Log.e(TAG, String.format("PlacePicker Exception: %s", e.getMessage()));
}
}
/***
* Called when the Place Picker Activity returns back with a selected place (or after canceling)
*
* @param requestCode The request code passed when calling startActivityForResult
* @param resultCode The result code specified by the second activity
* @param data The Intent that carries the result data.
*/
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == PLACE_PICKER_REQUEST && resultCode == RESULT_OK) {
Place place = PlacePicker.getPlace(this, data);
if (place == null) {
Log.i(TAG, "No place selected");
return;
}
String placeID = place.getId();
// Insert a new place into DB
ContentValues contentValues = new ContentValues();
contentValues.put(PlaceContract.PlaceEntry.COLUMN_PLACE_ID, placeID);
getContentResolver().insert(PlaceContract.PlaceEntry.CONTENT_URI, contentValues);
// Get live data information
refreshPlacesData();
}
}
@Override
public void onResume() {
super.onResume();
// Initialize location permissions checkbox
CheckBox locationPermissions = (CheckBox) findViewById(R.id.location_permission_checkbox);
if (ActivityCompat.checkSelfPermission(MainActivity.this,
android.Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
locationPermissions.setChecked(false);
} else {
locationPermissions.setChecked(true);
locationPermissions.setEnabled(false);
}
// Initialize ringer permissions checkbox
CheckBox ringerPermissions = (CheckBox) findViewById(R.id.ringer_permissions_checkbox);
NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
// Check if the API supports such permission change and check if permission is granted
if (android.os.Build.VERSION.SDK_INT >= 24 && !nm.isNotificationPolicyAccessGranted()) {
ringerPermissions.setChecked(false);
} else {
ringerPermissions.setChecked(true);
ringerPermissions.setEnabled(false);
}
}
public void onRingerPermissionsClicked(View view) {
Intent intent = new Intent(android.provider.Settings.ACTION_NOTIFICATION_POLICY_ACCESS_SETTINGS);
startActivity(intent);
}
public void onLocationPermissionClicked(View view) {
ActivityCompat.requestPermissions(MainActivity.this,
new String[]{android.Manifest.permission.ACCESS_FINE_LOCATION},
PERMISSIONS_REQUEST_FINE_LOCATION);
}
public static interface ClickListener{
public void onClick(View view,int position);
public void onLongClick(View view,int position);
}
class RecyclerTouchListener implements RecyclerView.OnItemTouchListener{
private ClickListener clicklistener;
private GestureDetector gestureDetector;
public RecyclerTouchListener(Context context, final RecyclerView recycleView, final ClickListener clicklistener){
this.clicklistener=clicklistener;
gestureDetector=new GestureDetector(context,new GestureDetector.SimpleOnGestureListener(){
@Override
public boolean onSingleTapUp(MotionEvent e) {
return true;
}
@Override
public void onLongPress(MotionEvent e) {
View child=recycleView.findChildViewUnder(e.getX(),e.getY());
if(child!=null && clicklistener!=null){
clicklistener.onLongClick(child,recycleView.getChildAdapterPosition(child));
}
}
});
}
@Override
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e) {
View child=rv.findChildViewUnder(e.getX(),e.getY());
if(child!=null && clicklistener!=null && gestureDetector.onTouchEvent(e)){
clicklistener.onClick(child,rv.getChildAdapterPosition(child));
}
return false;
}
@Override
public void onTouchEvent(RecyclerView rv, MotionEvent e) {
}
@Override
public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
}
}
}
PlaceDbhelper.java类
public class PlaceDbHelper extends SQLiteOpenHelper {
// The database name
private static final String DATABASE_NAME = "location.db";
PlaceListAdapter obj1;
// If you change the database schema, you must increment the database version
private static final int DATABASE_VERSION = 1;
// Constructor
public PlaceDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase sqLiteDatabase) {
// Create a table to hold the places data
final String SQL_CREATE_PLACES_TABLE = "CREATE TABLE " + PlaceEntry.TABLE_NAME + " (" +
PlaceEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
PlaceEntry.COLUMN_PLACE_ID + " TEXT NOT NULL, " +
"UNIQUE (" + PlaceEntry.COLUMN_PLACE_ID + ") ON CONFLICT REPLACE" +
"); ";
sqLiteDatabase.execSQL(SQL_CREATE_PLACES_TABLE);
}
String pe=PlaceEntry._ID.toString();
@Override
public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {
// For now simply drop the table and create a new one.
sqLiteDatabase.execSQL("DROP TABLE IF EXISTS " + PlaceEntry.TABLE_NAME);
onCreate(sqLiteDatabase);
}
PlacelistAdapter.java类
public class PlaceListAdapter extends
RecyclerView.Adapter<PlaceListAdapter.PlaceViewHolder> {
private Context mContext;
private PlaceBuffer mPlaces;
PlaceDbHelper obj1;
RecyclerView recycleview;
public PlaceListAdapter(Context context, PlaceBuffer places) {
this.mContext = context;
this.mPlaces = places;
}
@Override
public PlaceViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// Get the RecyclerView item layout
LayoutInflater inflater = LayoutInflater.from(mContext);
View view = inflater.inflate(R.layout.item_place_card, parent, false);
//final Activity activity;
return new PlaceViewHolder(view);
}
@Override
public void onBindViewHolder(PlaceViewHolder holder, int position) {
String placeName = mPlaces.get(position).getName().toString();
String placeAddress = mPlaces.get(position).getAddress().toString();
holder.nameTextView.setText(placeName);
holder.addressTextView.setText(placeAddress);
}
public void swapPlaces(PlaceBuffer newPlaces) {
mPlaces = newPlaces;
if (mPlaces != null) {
// Force the RecyclerView to refresh
this.notifyDataSetChanged();
}
}
@Override
public int getItemCount() {
if (mPlaces == null) return 0;
return mPlaces.getCount();
}
/**
* PlaceViewHolder class for the recycler view item
*/
class PlaceViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView nameTextView;
TextView addressTextView;
public PlaceViewHolder(final View itemView) {
super(itemView);
nameTextView = (TextView) itemView.findViewById(R.id.name_text_view);
addressTextView = (TextView) itemView.findViewById(R.id.address_text_view);
}
@Override
public void onClick(View v) {
}
答案 0 :(得分：0)
我有你的解决方案，你需要从db中删除行，然后从你的arraylist中删除，然后通知你适配器。如下。
在PlaceDbhelper.java班级
public void removePlace(String placeId){
SQLiteDatabase db = this.getWritableDatabase();
db.delete(PlaceEntry.TABLE_NAME, PlaceEntry.COLUMN_PLACE_ID + "=\"" + placeId+"\"", null) ;
}
现在在点击删除
时将此方法设置为警告private void deletePlace(int position){
PlaceDbhelper dbHelper = new PlaceDbhelper(MainActivity.this);
dbHelper.removePlace(placeArraylist.get(position).getPlaceId());
placeArraylist.remove(position);
mAdapter.notifyDataSetChanged();
}
希望这会对您有所帮助，如果这样可以解决您的问题，请批准。询问您是否需要帮助。