ItemListener is not changing value Java

Question

I made this code which should change the value in a JLabel after selecting an item from a combobox. When I run the application the appears in the JLabel but when I select other value in combobox, the value in JLabel isn't changing. Do anyone know where the problem is?

comboBox = new JComboBox<String>();
    comboBox.setBounds(172, 50, 106, 22);
    frmAccountPayable.getContentPane().add(comboBox);

    comboBox.addItemListener(new ItemListener(){

    public void itemStateChanged(ItemEvent event) { 
        if (event.getStateChange() == ItemEvent.SELECTED) {
            Object item = event.getItem();
            String expenseCode = item.toString();

            try {
                String sql2 = "SELECT `Account No`, `Expense Code` FROM `database`.`expense_code_master` " + 
                        "WHERE `Expense Code` = '" + expenseCode + "'";
                PreparedStatement pst2 = conn.prepareStatement(sql2);
                ResultSet rs = pst2.executeQuery();
                String accNo1 = null;
                while (rs.next()){
                    accNo1 = rs.getString("Account No");
                }

                lblTesting = new JLabel(accNo1);
                lblTesting.setBounds(496, 49, 106, 22);
                frmAccountPayable.getContentPane().add(lblTesting);

            }catch (Exception ex) {
                System.out.println("Error: "+ex);

            }
        }
    }
});

Answer 1

If you already have a JLabel in your component, you don't need to recreate one for each state change.

Move that part to where you also add your comboBox:

lblTesting = new JLabel(accNo1);
lblTesting.setBounds(496, 49, 106, 22);
frmAccountPayable.getContentPane().add(lblTesting);

But with the default constructor.

And instead of adding a new label each time, simply call:

lblTesting.setText(accNo1);

That being said, I guess that in your example you add new label, but only the first is displayed - depending on your layout.