What to do with Cursor after a SQLite query?

This is my first time using a database and I'm not really sure how this works. I made the database and made a query that returns a cursor and... now what? What is a cursor, really? Can I just use that to navigate through my data or do I have to put it in开发者_JAVA百科 an ArrayList or ListActivity or what?

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You need to iterate the cursor to get your results.

Use cursor.moveToFirst() and/or cursor.moveToNext() (with a while loop). Then you can use the getX() method, like cursor.getInt() or cursor.getString().

For example, ir your are expecting one result from your query:

if (cursor.moveToFirst()) {
    String name = cursor.getString(cursor.getColumnIndex('NAME'));
    int age = cursor.getInt(cursor.getColumnIndex('AGE'));
} else {
    // oops nothing found!
}

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First call cursor.moveToFirst(). Each time you call cursor.moveToNext() it will move to the next row. Make sure when you are done with your cursor you call cursor.deactivate() or you will get errors in your log cat.

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Iterate over the returned Cursor instance

public List<Object[]> cursorToTableRows(Cursor cursor) {
        List<Object[]> result = new ArrayList<Object[]>(cursor.getCount());

        cursor.move(0);
        cursor.moveToNext();
        while (cursor.isAfterLast() == false) {
            Object[] tableRow = new Object[cursor.getColumnCount()];
            for(int i=0; i<cursor.getColumnNames().length; i++) {
                int columnIndex = cursor.getColumnIndex(cursor.getColumnName(i));
                String columnValue = cursor.getString(columnIndex);
                tableRow[i] = columnValue;
            }
            result.add(tableRow);
            cursor.moveToNext();
        }

        cursor.close();

        return result;
    }

Then create the desired objects.

public List<Vehicle> getVehicles() {
        List<Vehicle> vehicles = new ArrayList<Vehicle>();
        Cursor cursor = null;
        List<Object[]> objects = cursorToTableRows(cursor);
        for(Object[] row : objects) {
            int i=0;
            Vehicle vehicle = new Vehicle(row[i++].toString(), row[i++].toString()));
            vehicles.add(vehicle)
        }
        return vehicles;
    }

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from Developer.android: This interface provides random read-write access to the result set returned by a database query.

In other words: query returns you a set of data represented by a cursor. First you need to make sure you got a valid cursor (not null) and then try to move it to desired position in the data set (use moveToXXX methods). In order to obtain data pointed by cursor use getXXX methods. When done using it make sure to call close to release resources.

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According to this link it looks like you can iterate through the query return using something like:

cursor.next();

And grab the data at the location you are looking for using:

cursor.getString(0)

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After you successfully have your Cursor setup, you would typically want to display that to a view in some form.

Have a look at the following answer for a detailed, but simple example of using a Cursor Adapter to pair up your newly-minted Cursor with your desired XML View:

https://stackoverflow.com/a/20532937/293280