Java Tips - How to use Item Events in Swing

Item events occur when an item is selected or deselected on any of the following components: JButton, JCheckBox, JComboBox, or JRadioButton. A class must implement the ItemListener interface in order to handle these events.


import java.awt.event.*;

import javax.swing.*;

import java.awt.*;



public class SelectItem extends JFrame implements ItemListener {

    BorderLayout bord = new BorderLayout();

    JTextField result = new JTextField(27);

    JComboBox pick = new JComboBox();



    public SelectItem() {

        super("Select Item");

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        pick.addItemListener(this);

        pick.addItem("Navigator");

        pick.addItem("Internet Explorer");

        pick.addItem("Opera");

        pick.setEditable(false);

        result.setHorizontalAlignment(SwingConstants.CENTER);

        result.setEditable(false);

        JPanel pane = new JPanel();

        pane.setLayout(bord);

        pane.add(result, "South");

        pane.add(pick, "Center");

        setContentPane(pane);

        pack();

        setVisible(true);

    }



    public static void main(String[] arguments) {

        JFrame frame = new SelectItem();

    }



    public void itemStateChanged(ItemEvent evt) {

        Object source = evt.getSource();

        if (source == pick) {

            Object newPick = evt.getItem();

            result.setText(newPick.toString() + " is the selection.");

        }

        repaint();

    }

}

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