Question

I create an array of combo boxes in a for loop like so:

for(int i = 0; i < 5; i++) {
  ...
  comboStudy[i] = new JComboBox(studyModel);
  comboStudy[i].addActionListener(new studyListener());
  comboStudy[i].setActionCommand("" + i);
  ...
}

The listener is an instance inner class:

public class studyListener implements ActionListener {
  public void actionPerformed(ActionEvent evt) {  
    int i = Integer.parseInt(evt.getActionCommand());

    // do some stuff that requires i and also access 
    // to the instance members of the containing class
  }
}

The problem I now face is that whenever I make a selection at run time in comboStudy[0] the action event gets fired 5 times. The first time i is 4, decreasing each time until it gets to 0.

I also tried it using an ItemListener, but it has the same problem.

Please help!

Answer 1

This is because you are using the same ComboBoxModel in all of your JComboBoxes.

Each JComboBox is a listener of the ComboxBoxModel and the ComboBoxModel will notify each listener whenever there is a change to the data model. When you select an item in a JComboBox, the ComboBoxModel changes which in turn fires events to each JComboBox. This is why you see events occurring on each JComboBox.