How to count number of JCheckboxes checked?

Question

I have 11 different checkboxes in my JFrame and want to be able to get a number whenever one is checked for how many total are checked. I know how to set up an ItemListener

Answer 1

you can keep a global counter countChecked and make the frame implements ItemListener

for all the JCheckBox in your frame chkBox.addItemListener(this) and handle the events

public class MyFrame extends JFrame implements ItemListener{

private int countChecked = 0;
private JPanel contentPane;
    public MyFrame() {
    contentPane = new JPanel();
    setContentPane(contentPane);
    JCheckBox chckbx = new JCheckBox("New check box");
    contentPane.add(chckbx, BorderLayout.CENTER);
    chckbx.addItemListener(this);
}

@Override
public void itemStateChanged(ItemEvent ie) {
    if(ie.getSource().getClass() == JCheckBox.class)
    {
        if(ie.getStateChange() == ie.SELECTED)
            countChecked++;
        else if(ie.getStateChange() == ie.DESELECTED)
            countChecked--;
    }

} 
}