在android中通過Recyclerview從sqlite數據庫中刪除記錄

Question

我制作了一個應用程序，允許用戶通過位置選擇器添加位置並將它們添加到 SQLite 數據庫中。我在 recyclerview 中顯示這些位置。 為了從recyclerview中刪除一個項目，這是我目前所做的。

1) 用戶在 recyclerview 中長按一個項目，然后出現帶有 2 個按鈕（刪除和取消）的警告對話框。

我不能做的：

1) 現在我不知道如何在用戶點擊刪除按鈕時從 recyclerview 和 SQLite 數據庫中刪除項目。

我已經搜索過它，但不知道它是如何實現的。 我發布了 MainActivity.java 類、PlaceDbhelper.java 類和 PlacelistAdapter.java 類的代碼。

MainActivity.java 類

    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 類

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 類

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

我為您提供了解決方案，您需要從 db 中刪除行，然后從您的 arraylist 中刪除，然后通知您適配器。 像下面。

在PlaceDbhelper.java類中使用此方法

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

現在在單擊DELETE時在警報中調用此方法

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

希望這會對您有所幫助，如果這解決了您的問題，請批准。 詢問您是否需要幫助。