通过Recyclerview在android系统

Question

删除SQLite数据库记录。我有一个应用程序，让用户通过位置选择器添加的位置，并将它们添加到SQLite的database.I我在显示这些recyclerview位置。为了从recyclerview删除一个项目，这是我迄今为止所做的。

1）用户在recyclerview项目长按，然后警报对话出现带有2个按钮（删除和取消）。

什么我不能做：

1）现在我不知道如何从recyclerview和SQLite数据库，当用户点击删除按钮删除项目。

...我已经寻找，但没有它如何可以实现。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) { 

    } 

Answer 1

我已经为你解决，你需要从数据库中删除行然后从您的数据列表中删除，并在它通知您的适配器后。如下所示。

使用此方法在PlaceDbhelper.java类

public void removePlace(String placeId){ 
     SQLiteDatabase db = this.getWritableDatabase(); 
     db.delete(PlaceEntry.TABLE_NAME, PlaceEntry.COLUMN_PLACE_ID + "=\"" + placeId+"\"", null) ; 
} 

现在调用警报此方法时点击DELETE

private void deletePlace(int position){ 
     PlaceDbhelper dbHelper = new PlaceDbhelper(MainActivity.this); 
     dbHelper.removePlace(placeArraylist.get(position).getPlaceId()); 
     placeArraylist.remove(position); 
     mAdapter.notifyDataSetChanged(); 
} 

希望这会帮助你，如果这个解决您的问题化妆它批准了。询问你是否需要帮助。