title: Attempt to reopen an already-closed object sqlitedatabase
body: <p>I have a databaseHandler. I need to count the rows in table. App crashes by this error: <code>android attempt to reopen an already-closed object sqlitedatabase</code>.<br>
  I simply use this code in activity:</p>
  
  <pre><code>db.getContactsCount();
  </code></pre>
  
  <p>But app crashes. Furthemore I want to reset the tables (delete table rows). I added the method  below: </p>
  
  <pre><code>public void deleteTable() {
          SQLiteDatabase db = this.getWritableDatabase();
          db.delete("contacts", null, null);
      }
  </code></pre>
  
  <p>It works good but I can't use this one:</p>
  
  <pre><code>@Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
      // Drop older table if existed
      db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
  
      // Create tables again
      onCreate(db);
  }
  </code></pre>
  
  <p>This is the databasehandler:</p>
  
  <pre><code>public class DatabaseHandler extends SQLiteOpenHelper {
  
  // All Static variables
  // Database Version
  private static final int DATABASE_VERSION = 1;
  
  // Database Name
  private static final String DATABASE_NAME = "contactsManager";
  
  // Contacts table name
  private static final String TABLE_CONTACTS = "contacts";
  
  // Contacts Table Columns names
  private static final String KEY_ID = "id";
  private static final String KEY_NAME = "name";
  private static final String KEY_PH_NO = "phone_number";
  
  public DatabaseHandler(Context context) {
      super(context, DATABASE_NAME, null, DATABASE_VERSION);
  }
  
  // Creating Tables
  @Override
  public void onCreate(SQLiteDatabase db) {
      String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
              + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
              + KEY_PH_NO + " TEXT" + ")";
      db.execSQL(CREATE_CONTACTS_TABLE);
  }
  
  // Upgrading database
  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
      // Drop older table if existed
      db.execSQL("DROP TABLE IF EXISTS " + TABLE_CONTACTS);
  
      // Create tables again
      onCreate(db);
  }
  
  /**
   * All CRUD(Create, Read, Update, Delete) Operations
   */
  
  // Adding new contact
  void addContact(Contact contact) {
      SQLiteDatabase db = this.getWritableDatabase();
  
      ContentValues values = new ContentValues();
      values.put(KEY_NAME, contact.getName()); // Contact Name
      values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone
  
      // Inserting Row
      db.insert(TABLE_CONTACTS, null, values);
      db.close(); // Closing database connection
  }
  
  // Getting single contact
  Contact getContact(int id) {
      SQLiteDatabase db = this.getReadableDatabase();
  
      Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID,
              KEY_NAME, KEY_PH_NO }, KEY_ID + "=?",
              new String[] { String.valueOf(id) }, null, null, null, null);
      if (cursor != null)
          cursor.moveToFirst();
  
      Contact contact = new Contact(Integer.parseInt(cursor.getString(0)),
              cursor.getString(1), cursor.getString(2));
      // return contact
      return contact;
  }
  
  // Getting All Contacts
  public List&lt;Contact&gt; getAllContacts() {
      List&lt;Contact&gt; contactList = new ArrayList&lt;Contact&gt;();
      // Select All Query
      String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;
  
      SQLiteDatabase db = this.getWritableDatabase();
      Cursor cursor = db.rawQuery(selectQuery, null);
  
      // looping through all rows and adding to list
      if (cursor.moveToFirst()) {
          do {
              Contact contact = new Contact();
              contact.setID(Integer.parseInt(cursor.getString(0)));
              contact.setName(cursor.getString(1));
              contact.setPhoneNumber(cursor.getString(2));
              // Adding contact to list
              contactList.add(contact);
          } while (cursor.moveToNext());
      }
  
      // return contact list
      return contactList;
  }
  
  // Updating single contact
  public int updateContact(Contact contact) {
      SQLiteDatabase db = this.getWritableDatabase();
  
      ContentValues values = new ContentValues();
      values.put(KEY_NAME, contact.getName());
      values.put(KEY_PH_NO, contact.getPhoneNumber());
  
      // updating row
      return db.update(TABLE_CONTACTS, values, KEY_ID + " = ?",
              new String[] { String.valueOf(contact.getID()) });
  }
  
  // Deleting single contact
  public void deleteContact(Contact contact) {
      SQLiteDatabase db = this.getWritableDatabase();
      db.delete(TABLE_CONTACTS, KEY_ID + " = ?",
              new String[] { String.valueOf(contact.getID()) });
      db.close();
  }
  
  
  // Getting contacts Count
  public int getContactsCount() {
      String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;
      SQLiteDatabase db = this.getReadableDatabase();
      Cursor cursor = db.rawQuery(countQuery, null);
      cursor.close();
  
      // return count
      return cursor.getCount();
  }
  
  public void Upgrade (SQLiteDatabase db, int oldVersion, int newVersion) {
      String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
              + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
              + KEY_PH_NO + " TEXT" + ")";
      db.execSQL(CREATE_CONTACTS_TABLE);
  }
  
  // Deleting single contact
      public void deleteTable() {
          SQLiteDatabase db = this.getWritableDatabase();
          db.delete("contacts", null, null);
      }
  }
  </code></pre>