CursorIndexOutOfBounds Exception: Index 0 requested, with a size of 0

Question

I tried to read the SQLite database column and store each values in an String array. I did the following but it returned exception cursoroutofbounds. Help me figure out what I'm doing wrong?

 public String[] getPlaces(){
   SQLiteDatabase db = this.getReadableDatabase();

    String [] columns = {"place1"};
    c = db.query("rates_table", columns, null, null, null, null, null);
    String[] places = new String[c.getColumnCount()];
    c.moveToNext();

    for(int i=0; i<c.getColumnCount(); i++)
        places[i] = c.getString(i);

    return places;
}

Answer 1

I worked out for sometime and found out the solution:

 public String[] getPlaces(){
        SQLiteDatabase db = this.getReadableDatabase();

        String [] columns = {"place1"};
        c = db.query("rates_table", columns, null, null, null, null, null);

        c.moveToFirst();
        ArrayList<String> places = new ArrayList<String>();
        while(!c.isAfterLast()) {
            places.add(c.getString(c.getColumnIndex("place1")));
            c.moveToNext();
        }
        c.close();
        return places.toArray(new String[places.size()]);

    }

Answer 2

Here :

String[] places = new String[c.getColumnCount()];

c.getColumnCount() will return count of column in row instead of number of rows in column. use c.getCount() to initialize places Array:

String[] places = new String[c.getCount()];

Or use ArrayList .

Answer 3

You need to change your query and further processing at multiple places. Rectify your third parameter of query method to a proper where clause or keep it null. Loop through the cursor properly and add it to your String.

public String[] getPlaces(){
    SQLiteDatabase db = this.getReadableDatabase();

    String [] columns = {"place1"};
    c = db.query("rates_table", columns, null, null, null, null, null);


    if (c.getCount() > 0) {   
       String[] places = new String[c.getCount()];
       int i=0;
       c.moveToFirst();
       do {
         places[i] = c.getString(c.getColumnIndex(0))); 
       } while (c.moveToNext());
       return places;
    }
    c.close();
    db.close();


}

Answer 4

First you have an issue with c = db.query("rates_table", columns, "place1", null, null, null, null);

The third parameter will result in no rows being selected.

You could use c = db.query("rates_table", columns, null, null, null, null, null); , which would return all rows.

Or you could use c = db.query("rates_table", columns, "place1 = 'myplace'", null, null, null, null);, in which case only rows that have the value myplace in the column place1 would be shown.

The best practice way is to use the 3rd and 4th parameter in conjunction where you use ? placeholders in the 3rd parm (e.g "place1=?") and corresponding args in the 4th parameter (e.g. new String[]{"myplace"}), so to replicate the previous query you could have c = db.query("rates_table", columns, "place1=?", new String[]{"myplace}, null, null, null);

Using c.moveToNext, will try to move to the next (initially the first) row of the cursor. However, if it cannot move (i.e. there are no rows, as would be the case as described above) it will not fail, rather it returns false (true if the cursor could be moved).

So You need to check this otherwise, in the case of no rows, an attempt to access a row will fail with Cursor out of bounds Index 0 requested, with a size of 0 (i.e. you requested the first (index 0) when the size of the cursors (number of rows) is 0.

There are various ways to check.

However I suspect you will then wonder why your loop only displays 1 column. That would be because you have said in the query to just get 1 column.

If you changed the query's 2nd parameter to null, it would get all columns.

At a guess you want to return an array of all places.

Assuming this then :-

// get Cursor with all rows(3rd parm null) for the place1 column (2nd parm)
c = db.query("rates_table", columns, null, null, null, null, null);

// Create String array according to the number of rows returned.
String[] places = new String[c.getCount()];

// loop through all rows setting the respective places element with the 
// value obtained from the Cursor
while (c.moveToNext) {
    places[c.getPosition()] = csr.getString(csr.getColumnIndex("place1")); 
}

csr.close(); // Should always close a Cursor
return places;