CODEWITHSUNDEEP
javaswingjcomboboxitemlistener
Allain Lalonde
Allain Lalonde

Reputation: 93438

JComboBox Selection Change Listener?

I'm trying to get an event to fire whenever a choice is made from a JComboBox.

The problem I'm having is that there is no obvious addSelectionListener() method.

I've tried to use actionPerformed(), but it never fires.

Short of overriding the model for the JComboBox, I'm out of ideas.

How do I get notified of a selection change on a JComboBox?**

Edit: I have to apologize. It turns out I was using a misbehaving subclass of JComboBox, but I'll leave the question up since your answer is good.

Upvotes: 174

Views: 396511

Answers (8)

Dardion
Dardion

Reputation: 53

I use this:

    cb = new JComboBox<String>();
    cb.setBounds(10, 33, 46, 22);
    panelConfig.add(cb);
    for(int i = 0; i < 10; ++i)
    {
        cb.addItem(Integer.toString(i));
    }
    cb.addItemListener(new ItemListener()
    {
        @Override
        public void itemStateChanged(ItemEvent e)
        {
            if(e.getID() == temEvent.ITEM_STATE_CHANGED)
            {
                if(e.getStateChange() == ItemEvent.SELECTED)
                {
                    JComboBox<String> cb = (JComboBox<String>) e.getSource();
                    String newSelection = (String) cb.getSelectedItem();
                    System.out.println("newSelection: " + newSelection);
                }
            }
        }
    });

Upvotes: 3

Mehmet Onar
Mehmet Onar

Reputation: 353

you can do this with jdk >= 8

getComboBox().addItemListener(this::comboBoxitemStateChanged);

so

public void comboBoxitemStateChanged(ItemEvent e) {
    if (e.getStateChange() == ItemEvent.SELECTED) {
        YourObject selectedItem = (YourObject) e.getItem();
        //TODO your actitons
    }
}

Upvotes: 4

Ahuramazda
Ahuramazda

Reputation: 437

Here is creating a ComboBox adding a listener for item selection change:

JComboBox comboBox = new JComboBox();

comboBox.setBounds(84, 45, 150, 20);
contentPane.add(comboBox);

JComboBox comboBox_1 = new JComboBox();
comboBox_1.setBounds(84, 97, 150, 20);
contentPane.add(comboBox_1);
comboBox.addItemListener(new ItemListener() {
    public void itemStateChanged(ItemEvent arg0) {
        //Do Something
    }
});

Upvotes: 15

JavaKeith
JavaKeith

Reputation: 123

You may try these

 int selectedIndex = myComboBox.getSelectedIndex();

-or-

Object selectedObject = myComboBox.getSelectedItem();

-or-

String selectedValue = myComboBox.getSelectedValue().toString();

Upvotes: 8

jodonnell
jodonnell

Reputation: 50497

It should respond to ActionListeners, like this:

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

@John Calsbeek rightly points out that addItemListener() will work, too. You may get 2 ItemEvents, though, one for the deselection of the previously selected item, and another for the selection of the new item. Just don't use both event types!

Upvotes: 197

Craig Wayne
Craig Wayne

Reputation: 5068

I was recently looking for this very same solution and managed to find a simple one without assigning specific variables for the last selected item and the new selected item. And this question, although very helpful, didn't provide the solution I needed. This solved my problem, I hope it solves yours and others. Thanks.

How do I get the previous or last item?

Upvotes: 4

Viacheslav
Viacheslav

Reputation: 5603

Code example of ItemListener implementation

class ItemChangeListener implements ItemListener{
    @Override
    public void itemStateChanged(ItemEvent event) {
       if (event.getStateChange() == ItemEvent.SELECTED) {
          Object item = event.getItem();
          // do something with object
       }
    }       
}

Now we will get only selected item.

Then just add listener to your JComboBox

addItemListener(new ItemChangeListener());

Upvotes: 186

John Calsbeek
John Calsbeek

Reputation: 36547

I would try the itemStateChanged() method of the ItemListener interface if jodonnell's solution fails.

Upvotes: 24

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