java.lang.NullPointerException in doInBackground(final String... args)

Question

I have this code that converts the .db file to .csv and saves in sdcard of my android device. Unfortunately the activity stops and causes a java.lang.NullPointerException in doInBackground method

protected Boolean doInBackground(final String... args) {
    File dbFile=getDatabasePath(logindatabaseadapter3.DATABASE_NAME);
    //  DbClass DBob = new DbClass(MyDatabaseActivity.this);
    File exportDir = new File(Environment.getExternalStorageDirectory(), "");
    if (!exportDir.exists()) {
        exportDir.mkdirs();
    }

    File file = new File(exportDir, "designtry.csv");

    try {
        file.createNewFile();
        CSVWriter csvWrite = new CSVWriter(new FileWriter(file));

        //SQLiteDatabase db = DBob.getReadableDatabase();
        Cursor curCSV=db.rawQuery("select * from " + Table_Name,null);
        //  Cursor curCSV = db.rawQuery("SELECT * FROM table_ans12",null);

        csvWrite.writeNext(curCSV.getColumnNames());

        while(curCSV.moveToNext()) {
            String arrStr[] ={curCSV.getString(0),curCSV.getString(1),curCSV.getString(2),curCSV.getString(3),curCSV.getString(4),
                    curCSV.getString(5),curCSV.getString(6),curCSV.getString(7),curCSV.getString(8),curCSV.getString(9),
                    curCSV.getString(10),curCSV.getString(11),curCSV.getString(12),curCSV.getString(13),curCSV.getString(14),
                    curCSV.getString(15),curCSV.getString(16),curCSV.getString(17),curCSV.getString(18),curCSV.getString(19)};


            csvWrite.writeNext(arrStr);

        }

        csvWrite.close();
        curCSV.close();
        return true;

    }

    catch(SQLException sqlEx) {
        Log.e("MainActivity", sqlEx.getMessage(), sqlEx);
        return false;
    }
    catch (IOException e) {
        Log.e("MainActivity", e.getMessage(), e);
        return false;
    }
}

post the stack trace. should you not mention the folder name File exportDir = new File(Environment.getExternalStorageDirectory(), "my folder");? — Raghunandan
– Raghunandan, Commented Jun 19, 2013 at 7:11
@Raghunandan he wants to store inside sdcard, so I think is better File exportDir = Environment.getExternalStorageDirectory() — Blackbelt
– Blackbelt, Commented Jun 19, 2013 at 7:13
No the above correction does not make a difference, I am able to export the file in my sdcard but it is empty and the application crashes. The error occurs in this line — Archie Jain
– Archie Jain, Commented Jun 19, 2013 at 7:21
Cursor curCSV=db.rawQuery("select * from " + Table_Name,null); — Archie Jain
– Archie Jain, Commented Jun 19, 2013 at 7:22

Archie Jain · Accepted Answer · 2013-06-21 10:03:30Z

0

I found the solution I was simply placing it in the wrong class.

answered Jun 21, 2013 at 10:03

Archie Jain

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