public void moveToQ1() {

    index = customerList.getSelectedIndex();
    if (index != -1) {

        browsing.dequeue(customerList);
        q1.enqueue(browsing, customerList, queue1, index);

    }
}

public void enqueue(QueLine queline, JList list1, JList list2, int index) {

    DefaultListModel<Customer> browseModel = (DefaultListModel<Customer>) list1.getModel();
    DefaultListModel<Customer> queueModel = (DefaultListModel<Customer>) list2.getModel();

    int selectedIndex = index;
    System.out.printf("%dn", selectedIndex);

    if(selectedIndex >= -1) {
        queueModel.addElement(browseModel.getElementAt(selectedIndex));
    }


}