title: JComboBox, ActionListener, How do I really use them?
body: <p>Im currently learning java and stuck onto JComboBox.
  I have a feel things that I am trying out and hitting the wall for the pass 4 hours.</p>
  
  <p>I am trying to let a user select 1-10 from a ComboBox.
  How do I get the value of the combobox?
  The value of the combo box is equivalent to quantity.</p>
  
  <p>So I have another value which is maybe $10.
  If the user choose quantity 2.</p>
  
  <p>I want to get the value of what the user choose, then take the value of $10 and times it by 2.</p>
  
  <p>The result which is $20 will be displayed on the JTextField.</p>
  
  <p>Please help :(</p>
  
  <pre><code>public class Panel extends JPanel {
  
      public Panel(){
          JPanel test = new JPanel(new GridBagLayout());
  
          String[] quantities1 = {"0","1","2","3","4","5","6","7","8","9","10"};
          JComboBox quantitiesCB = new JComboBox(quantities1);
          quantitiesCB.addActionListener(
                  new ActionListener(){
                      public void actionPerformed(ActionEvent e){
                          JComboBox combo = (JComboBox)e.getSource();
                          String currentQuantity = (String)combo.getSelectedItem();
                      }
                  }            
          );
  
          JTextField result = new JTextField();
  
          setLayout(new GridBagLayout());
          setPreferredSize(new Dimension(640,480));
          GridBagConstraints gbc = new GridBagConstraints();
  
          gbc.gridx = 0;
          gbc.gridy = 0;
          gbc.weightx = 0.1;
          gbc.weighty = 0.1;
          gbc.fill = GridBagConstraints.HORIZONTAL;
          gbc.anchor = GridBagConstraints.NORTH;
          add(quantitiesCB, gbc);
      } 
  }
  </code></pre>