Android: Content Provider fügt zwei Zeilen gleichzeitig hinzu

Question

Ich folgte diesem tutorial auf Content Providers, und es hat gut funktioniert. Ich habe versucht, etwas selbst und Loader verwendet, um die Daten zu laden. Und ich kann Folgendes nicht erreichen:

• Zeigt nicht den "Text" der Nachricht, nur die ID und Zeitstempel. (Auch wenn Zeitstempel Zeichenfolge enthalten aber Zahlen)
• größte Problem: 2 Reihen der gleichen Werte werden addiert einen nach dem anderen

Also jedes Mal wenn ich auf die Nachricht Taste, fügen zwei Reihen. Dies ist die Logcat-Datei.

07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 1, , 1468526093018 
07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 2, , 1468526093018 
07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 3, , 1468526292717 
07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 4, , 1468526292717 
07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 5, , 1468696845898 
07-17 02:57:18.307 11619-11619/poketpixels.reminder D/DB: 6, , 1468696845898 

Hinweis, dass es keine Textanzeige für BODY ist und die Zeitstempel von zwei Reihen sind gleich. So natürlich, gleichzeitig geschaffen.

Es folgt die Aktivitätsdatei:

public class ActivityChat extends AppCompatActivity 
    implements LoaderManager.LoaderCallbacks<Cursor> { 

private static final int URL_LOADER = 0; 
String URL = "content://something/messages"; 
Button sendMessage; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_chat); 

    sendMessage = (Button)findViewById(R.id.btnSend); 

    getLoaderManager().initLoader(URL_LOADER, null, this); 

    sendMessage.setOnClickListener(new View.OnClickListener() { 
     @Override 
     public void onClick(View v) { 
      SendMessage(); 
     } 
    }); 

} 



public Loader<Cursor> onCreateLoader(int id, Bundle args) { 
    CursorLoader loader = new CursorLoader(
      this, 
      Uri.parse(URL), 
      null, 
      null, 
      null, 
      null); 

    return loader; 
} 



public void onLoadFinished(
     Loader<Cursor> loader, 
     Cursor c) { 

// LOADS ALL ROWS 
    if (c.moveToFirst()) { 
     do { 
      Log.d("DB", 
        c.getString(c.getColumnIndex(MessageProvider._ID)) + 
          ", " + c.getString(c.getColumnIndex(MessageProvider.BODY)) + 
          ", " + c.getString(c.getColumnIndex(MessageProvider.CREATED_AT)) + "\n" 
      ); 
     } while (c.moveToNext()); 
    } 

} 


@Override 
public void onLoaderReset(Loader<Cursor> loader) { 

} 

public void SendMessage() { 

    // Add a new message record 
    ContentValues values = new ContentValues(); 

    values.put(MessageProvider.BODY, 
      ((EditText)findViewById(R.id.eTmessageBody)).getText().toString()); 

    values.put(MessageProvider.CREATED_AT, 
      (System.currentTimeMillis())); 

    Log.d("DB", "SENT ALREADY"); 
    Uri messages = Uri.parse(URL); 

    Cursor c = getContentResolver().query(messages, null, null, null, "created_at"); 

    //loads only the last row 
    c.moveToLast(); 
    Log.d("LAST ROW",c.getString(c.getColumnIndex(MessageProvider._ID)) + 
      ", " + c.getString(c.getColumnIndex(MessageProvider.BODY)) + 
      ", " + c.getString(c.getColumnIndex(MessageProvider.CREATED_AT))); 

} 

}

MessageProvider.java

public class MessageProvider extends ContentProvider { 

static final String PROVIDER_NAME = "something"; 
static final String URL = "content://" + PROVIDER_NAME + "/messages"; 
public static final Uri CONTENT_URI = Uri.parse(URL); 

public static final String _ID = "_id"; 
public static final String BODY = "body"; 
public static final String CREATED_AT = "created_at"; 

private static HashMap<String, String> MESSAGES_PROJECTION_MAP; 

static final int MESSAGES = 1; 
static final int MESSAGE_ID = 2; 

static final UriMatcher uriMatcher; 
static { 
    uriMatcher = new UriMatcher(UriMatcher.NO_MATCH); 
    uriMatcher.addURI(PROVIDER_NAME, "messages", MESSAGES); 
    uriMatcher.addURI(PROVIDER_NAME, "messages/#", MESSAGE_ID); 
} 


/** 
* Database specific constant declarations 
*/ 
private SQLiteDatabase db; 
static final String DATABASE_NAME = "test"; 
static final String MESSAGES_TABLE_NAME = "message"; 
static final int DATABASE_VERSION = 1; 
static final String CREATE_DB_TABLE = 
     " CREATE TABLE " + MESSAGES_TABLE_NAME + 
       " (_id INTEGER PRIMARY KEY AUTOINCREMENT, " + 
       " body TEXT NOT NULL, " + 
       " created_at TEXT NOT NULL);"; 

/** 
* Helper class that actually creates and manages 
* the provider's underlying data repository. 
*/ 
private static class DatabaseHelper extends SQLiteOpenHelper { 
    DatabaseHelper(Context context) { 
     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     db.execSQL(CREATE_DB_TABLE); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + MESSAGES_TABLE_NAME); 
     onCreate(db); 
    } 
} 

@Override 
public boolean onCreate() { 
    Context context = getContext(); 
    DatabaseHelper dbHelper = new DatabaseHelper(context); 

    /** 
    * Create a write able database which will trigger its 
    * creation if it doesn't already exist. 
    */ 
    db = dbHelper.getWritableDatabase(); 
    return (db == null) ? false : true; 
} 

@Override 
public Uri insert(Uri uri, ContentValues values) { 

    final long objectId = db.insertOrThrow(MessageProvider.MESSAGES_TABLE_NAME, null, values); 
    final Uri newObjectUri = ContentUris.withAppendedId(CONTENT_URI, objectId); 
    getContext().getContentResolver().notifyChange(newObjectUri, null); 

    /** 
    * Add a new message record 
    */ 
    long rowID = db.insert(MESSAGES_TABLE_NAME, "", values); 

    /** 
    * If record is added successfully 
    */ 

    if (rowID > 0) { 
     Uri _uri = ContentUris.withAppendedId(CONTENT_URI, rowID); 
     getContext().getContentResolver().notifyChange(_uri, null); 
     return _uri; 
    } 
    throw new SQLException("Failed to add a record into " + uri); 
} 

@Override 
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { 
    SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); 
    qb.setTables(MESSAGES_TABLE_NAME); 


    switch (uriMatcher.match(uri)) { 
     case MESSAGES: 
      qb.setProjectionMap(MESSAGES_PROJECTION_MAP); 
      break; 

     case MESSAGE_ID: 
      qb.appendWhere(_ID + "=" + uri.getPathSegments().get(1)); 
      break; 

     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
    } 

    if (sortOrder == null || sortOrder == "") { 
     /** 
     * By default sort on time 
     */ 
     sortOrder = CREATED_AT; 
    } 
    Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, sortOrder); 

    /** 
    * register to watch a content URI for changes 
    */ 
    c.setNotificationUri(getContext().getContentResolver(), uri); 
    return c; 
} 


@Override 
public int delete(Uri uri, String selection, String[] selectionArgs) { 
    int count = 0; 


    //public int delete(String table, String whereClause, String[] whereArgs) { 

    final long objectId = db.delete(MessageProvider.MESSAGES_TABLE_NAME, null, null); 
    final Uri newObjectUri = ContentUris.withAppendedId(CONTENT_URI, objectId); 
    getContext().getContentResolver().notifyChange(newObjectUri, null); 


    switch (uriMatcher.match(uri)) { 
     case MESSAGES: 
      count = db.delete(MESSAGES_TABLE_NAME, selection, selectionArgs); 
      break; 

     case MESSAGE_ID: 
      String id = uri.getPathSegments().get(1); 
      count = db.delete(MESSAGES_TABLE_NAME, _ID + " = " + id + 
        (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs); 
      break; 

     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
    } 

    getContext().getContentResolver().notifyChange(uri, null); 
    return count; 
} 

@Override 
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) { 
    int count = 0; 


    final long objectId = db.insertOrThrow(MessageProvider.MESSAGES_TABLE_NAME, null, values); 
    final Uri newObjectUri = ContentUris.withAppendedId(CONTENT_URI, objectId); 
    getContext().getContentResolver().notifyChange(newObjectUri, null); 


    switch (uriMatcher.match(uri)) { 
     case MESSAGES: 
      count = db.update(MESSAGES_TABLE_NAME, values, selection, selectionArgs); 
      break; 

     case MESSAGE_ID: 
      count = db.update(MESSAGES_TABLE_NAME, values, _ID + " = " + uri.getPathSegments().get(1) + 
        (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""), selectionArgs); 
      break; 

     default: 
      throw new IllegalArgumentException("Unknown URI " + uri); 
    } 
    getContext().getContentResolver().notifyChange(uri, null); 
    return count; 
} 

@Override 
public String getType(Uri uri) { 
    switch (uriMatcher.match(uri)) { 
     /** 
     * Get all message records 
     */ 
     case MESSAGES: 
      return "vnd.android.cursor.dir/vnd.poketpixels.reminder.messages"; 

     /** 
     * Get a particular message 
     */ 
     case MESSAGE_ID: 
      return "vnd.android.cursor.item/vnd.poketpixels.reminder.messages"; 

     default: 
      throw new IllegalArgumentException("Unsupported URI: " + uri); 
    } 
} 
} 

So sind die beiden Probleme sind:

• Ich möchte Strings anzeigen.
• Zwei Reihen hinzugefügt zu einem bestimmten Zeitpunkt zu Datenbank

EDIT:

Zweites Problem ist gelöst. Ich kann die Zeichenfolgen jedoch immer noch nicht anzeigen. Zeigt in logcat null an.

Answer 1

Sie fügen Datensatz zweimal in der Einfügemethode ein. Entfernen

one by using :  final long objectId = db.insertOrThrow(MessageProvider.MESSAGES_TABLE_NAME, null, values); 


Another by : long rowID = db.insert(MESSAGES_TABLE_NAME, "", values); 

eine der oben Linie von Insert-Methode der Klasse MessageProvider.