所选组合框值两次添加到数组列表中

Question

I've populated the elements of a combo box using a SQL query and am writing the selected value to an arraylist. When I print out the elements of the arraylist, the value has been added twice. Does anybody know why this is, and how do I stop this from happening?

Extracts from the code:

resultSet = statement.executeQuery("SELECT name FROM menu WHERE category = 'beverage'");
while (resultSet.next())
{
    beverageJComboBox.addItem(resultSet.getString(1));
    System.out.printf("%s", resultSet.getString(1));
}

And for the adding ite to the ArrayList:

beverageJComboBox.addItemListener(
     new ItemListener()
     {
          public void itemStateChanged( ItemEvent event )
          {
              billItems.add((String)beverageJComboBox.getSelectedItem());
              System.out.printf("%s", billItems); 
          }
     }// end anonymous inner class
); 

(Very new to Java!)

Answer 1

Use ActionListener instead of ItemListener

    beverageJComboBox.addActionListener (new ActionListener () {
        public void actionPerformed(ActionEvent e) {
            ...
        }
    });

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Note: use distinct keyword in query itself to show the unique record in JComboBox .