Attempt to re-open an already-closed object: java.lang.IllegalStateException:?

I know this question has asked many times in SO,but i couldn't figure out my exact problem.

I am using the following code to get the data from the database(Table1) and update another Table2 based on retrieval value. Its working fine in some android versions but when i gone to test with Android 4.0.3. I am geting this java.lang.IllegalStateException:?.attempt to re-open an already-closed object at sum_cursor.moveToNext();.

I am using this code in AsyncTask.

 /** Sum of total matched values*/
            Cursor sum_cursor = db.gettotalMatchvalue(this);
             if(sum_cursor!=null)
             {
                 sum_cursor.moveToFirst();
                 for(int j=0; j<sum_cursor.getCount();j++)
                 {    
                     float totalmatchedscore = sum_cursor.getInt(0);
                     float totalingredients = Float.parseFloat(sum_cursor.getString(sum_cursor.getColumnIndex(APPDatabase.CK_TOTALINCREDIENTS)));
                     /**average = totalscore/totalingredients*/
                     double average = totalmatchedscore/totalingredients;
                     int id = Integer.parseInt(sum_cursor.getString(sum_cursor.getColumnIndex(APPDatabase.CK_ID))); 

                 db.updateAverage(id, average); 
                 sum_cursor.moveToNext(); //Here is the problem
                 }  
             }   
             db.close();  

My update method coding

/** Update average */
public void updateAverage(int id,double average)
{
    SQLiteDatabase db = getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(CK_FINALVALUE,average);
    db.update(TABLE, values,CK_ID+" = "+id , null);   
}

What i am doing wrong here?

I know many of you come across this situation. Could you help me guys.

Thanks for your help.

Answers


You can't update a table while iterating over the results of a query. There are good reasons for this; what if the data you are adding would cause a change to the data you're iterating over? Your cursor would not return valid data.

Trying to store data back into the table in updateAverage() is causing the problem. You should just remember the average value during your loop, and then update it once at the end after you've finished looping over your cursor.

To further explain the exact error you're getting: the act of inserting new data is causing the database to close all the cursors which are currently open, as a safety measure. So when you call sum_cursor.moveToNext() after updating the average, the cursor is a bit surprised to find that it's already been closed.


What if you comment out db.updateAverage(id, average) ?


You can achieve your goal with pure SQL it is faster and better from architecture point of View because all logic will be in one SQL transaction

REPLACE INTO table_where_to_put  SELECT *, (totalmatchedscore/totalingredients) as average  FROM table_with_input_data

Use REPLACE OR UPDATE


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