Bubble sort array of objects

Trying to bubble sort an array of 2 objects, the comments are what the 2 positions (0 and 1) contain. It does actually populate the array. When I'm comparing ownerArray[j] and ownerArray [j+1] I get a null pointer exception, because I'm referring to a null value because the array isn't that large. Any clue how to fix this while still being able to refer to the next position of the array?

 public void sortOwners() {
    try {
        model = (DefaultTableModel) SortedOwners.jTable1.getModel();
        model.setRowCount(0);

        populateOwners();

        size2 = ownerArray.length;

        // ownerArray[0]  = 9900000000000 Reenen Muller [email protected]
        //  ownerArray[1] = 8800000000000 John   Doe    [email protected]
        for (int i = 0; i < size2; i++) {
            for (int j = 1; j < size2 - i; j++) {

                if ((ownerArray[j].getFirstName()).compareTo(ownerArray[j + 1].getFirstName()) < 0) {

                    Owner temp3 = ownerArray[j];
                    ownerArray[j] = ownerArray[j + 1];
                    ownerArray[j + 1] = temp3;


                }

            }
        }

        viewAllOwners();

    } catch (Exception e) {
        e.printStackTrace();

    }