Android IllegalStateException：試圖重新打開一個已經關閉的對象：SQLiteDatabase

Question

我知道有這樣的幾個問題，但他們都似乎有不同的方法來解決這個問題，沒有解決我的問題。

我有我的主要活動工作得很好，加載數據庫和填充列表視圖。然後我打電話給第二個活動，當我嘗試加載列表視圖時出現問題。

我試過使用start/stop managingcursor(cursor)，即使它已被棄用，但它沒有解決問題。此外，我嘗試在我的主要活動中觸發光標和數據庫，然後再觸發下一個，但這也沒有幫助。

兩個類都從ListActivity延伸，並按照相同的順序：

public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main);   

    //Open db in writing mode 
    MySQLiteHelper.init(this); 
    MySQLiteHelper tpdbh = 
     new MySQLiteHelper(this, "DB", null, 1); 


    SQLiteDatabase db = tpdbh.getWritableDatabase(); 

    checkLocationAndDownloadData(); //this fires a Asynctask that calls method parseNearbyBranches shown bellow 

    //I load the data to the ListView in the postExecute method of the asynctask by calling: 
    /* 
    Cursor cursor = MysSQLiteHelper.getBranchesNames(); 
    adapter = new SimpleCursorAdapter(this, 
      R.layout.row, cursor, fields, new int[] { R.id.item_text },0); 
    setListAdapter(adapter); 
    */ 

    ListView lv = getListView(); 
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() { 
    @Override 
     public void onItemClick(AdapterView<?> listView, View view, 
      int position, long id) { 

     // Get the cursor, positioned to the corresponding row in the result set 
     Cursor cursor = (Cursor) listView.getItemAtPosition(position); 

     // Get the state's capital from this row in the database. 
     String branch_id = cursor.getString(cursor.getColumnIndexOrThrow("branch_id")); 

      cursor.close(); 

     openNextActivity(Integer.parseInt(branch_id)); 
     } 
     }); 
} 

//在另一個文件中：

private void parseNearbyBranches(JSONObject jo) throws JSONException 
{ 
if ( jo.has(jsonTitle) && 
      jo.has("company_id") && 
      jo.has("id") 
    ) { 
     String branch = jo.getString(jsonTitle); 


      MySQLiteHelper tpdbh = MySQLiteHelper.instance; 
      SQLiteDatabase db = tpdbh.getWritableDatabase(); 

      db.execSQL("INSERT INTO Branches (branch_id, name, company_id) " + 
        "VALUES ('" +jo.getInt("id")+"', '" + branch +"', '" +jo.getInt("company_id")+"')"); 

      db.close(); //no difference is I comment or uncomment this line 

    } 
} 

在MySQLiteHelper.java：

public static Cursor getBranchesNames() { 
     // TODO Auto-generated method stub 
     String[] columns = new String[] { "_id", "branch_id", "name", "company_id" }; 
     Cursor c = getReadDb().query(branchesTable, columns, null, null, null, null, 
       null);    
     return c; 
    } 

我的其他活動基本上是一樣的：

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

    //Read branch data from DB 
     int companyID = -1; 
     MySQLiteHelper.init(this);   

     String [] columns = new String [] {"company_id"}; 
     String [] args = {Integer.toString(branchID)}; 
     Cursor c = MySQLiteHelper.getReadDb().query(MySQLiteHelper.branchesTable, columns, "branch_id=?", args, null, null, null); //THIS QUERY WORKS JUST FINE 

     if (c.moveToFirst()) 
      companyID = Integer.parseInt(c.getString(0)); 
     c.close(); 

     if(companyID != -1) 
     { 
      new DownloadTask().execute(Integer.toString(companyID)); 
//where the Async task calls something just like NearByBranches shown above(but with different objects of course) 
//And the postExecute sets the listView: 
/* cursor = MySQLiteHelper.getAll(); 
    SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, 
      R.layout.row, cursor, fields, new int[] { R.id.item_text },0); 
    setListAdapter(adapter); 
*/ 
     } 

    } 
} 

在MySQLiteHelper.java：

public static Cursor getAll() { 
    // TODO Auto-generated method stub 
    String[] columns = new String[] { "_id","title", "points" }; 

//********IT IS IN THIS LINE WHERE I GET THE ERROR:******************** 
    Cursor c = getReadDb().query(theTable, columns, null, null, null, null, 
      null); 

    return c; 
} 

    public static SQLiteDatabase getReadDb() { 
     if (null == db) { 
      db = instance.getReadableDatabase(); 
     } 
     return db; 
    } 

我希望你能幫助我。謝謝！

Answer 1

我只是嘗試在parseNeabyBranches的類似方法中評論db.close，問題就解決了。然而，我沒有得到parseNearbyBranches（）中db.close（）的同樣錯誤，你能解釋我爲什麼嗎？

在parseNearbyBranches()您創建一個單獨的SQLiteDatabase對象有：

SQLiteDatabase db = tpdbh.getWritableDatabase(); 

由於這是一個不同的對象比getReadDb()返回的一個，你可以（也應該）將其關閉。基本規則是每次您撥打getWritableDatabase()和getReadableDatable()您必須有一個匹配的close()聲明。