A tabbed pane fires a change event whenever the selected tab is changed either by the user or programmatically.

    // Create the tabbed pane

    JTabbedPane pane = new JTabbedPane();

    // Add tabs...; see e830 向JTabbedPane中加入一个卡片

    // Register a change listener

    pane.addChangeListener(new ChangeListener() {

        // This method is called whenever the selected tab changes

        public void stateChanged(ChangeEvent evt) {

            JTabbedPane pane = (JTabbedPane)evt.getSource();

            // Get current tab

            int sel = pane.getSelectedIndex();

        }

    });