//
// another example of the Java AWT, showing use of Menu class.
// see class definition and main method for details.
//
import java.awt.* ;
import java.awt.event.* ;

//
// a MenuExample object is a CloseableFrame with a menu bar and a
//      Label.  the menu bar contains two pull-down menus, a
//      "main" menu with selections resembling those of a "file"
//      menu, and a "secondary" menu containing two submenus
//      with selections to enable/disable the elements in the
//      main menu.  when the user makes a selection, corresponding
//      text is displayed in the Label; if the selection is from
//      the secondary menu, the corresponding selection in the
//      main menu is enabled/disabled.
//
class MenuExample extends CloseableFrame {

        Label display = new Label("", Label.CENTER) ;
        
        MenuExample() {

                super("MenuExample") ;
                setLayout(new GridLayout(0,1)) ;

                setDisplay("ready for input -- hello, world!") ;
                add(display) ;

                // ---- "main" menu ----

                Menu m1 = new Menu("A file menu") ;

                // listener for regular items.
                ActionListener a1 = new ActionListener() {
                        public void actionPerformed(ActionEvent e) {
                                processCommand(e.getActionCommand()) ;
                        }
                } ;

                // listener for checkbox items.
                ItemListener i1 = new ItemListener() {
                        public void itemStateChanged(ItemEvent e) {
                                CheckboxMenuItem c =
                                        (CheckboxMenuItem) e.getSource() ;
                                processCheck(c) ;
                        }
                } ;

                // menu items
                m1.add("This is some text in the menu.") ;
                m1.add(makeMenuItem("Open", a1, "open")) ;
                m1.addSeparator() ;
                m1.add(makeMenuItem("Print", a1, "print", 'P')) ;
                m1.add(makeMenuItem("Save", a1, "save", 'S')) ;
                m1.addSeparator() ;
                m1.add(makeCheckboxMenuItem("checkbox 1", i1, "cb1")) ;
                m1.add(makeCheckboxMenuItem("checkbox 2", i1, "cb2")) ;

                // ---- "secondary" menu ----

                // two submenus to enable/disable events in the main
                //      menu.
                Menu m2 = new Menu("Change file menu") ;
                m2.add(makeEnableDisableMenu(m1, true, 
                        "Enable menu items") ) ;
                m2.add(makeEnableDisableMenu(m1, false, 
                        "Disable menu items") ) ;

                // ---- menu bar ----

                MenuBar mb = new MenuBar() ;
                mb.add(m1) ;
                mb.add(m2) ;
                setMenuBar(mb) ;

                // ---- end of setup ----

                pack() ;
                show() ;

        }

        // ---- methods to construct menu items ----

        MenuItem makeMenuItem(String label, ActionListener l) {
                MenuItem mi = new MenuItem(label) ;
                mi.addActionListener(l) ;
                return mi ;
        }

        MenuItem makeMenuItem(String label, ActionListener l,
                        String cmd) {
                MenuItem mi = makeMenuItem(label, l) ;
                mi.setActionCommand(cmd) ;
                mi.setName(cmd) ;
                return mi ;
        }

        MenuItem makeMenuItem(String label, ActionListener l,
                        String cmd, int shortCutKey) {
                MenuItem mi = makeMenuItem(label, l, cmd) ;
                mi.setShortcut(new MenuShortcut(shortCutKey)) ;
                return mi ;
        }

        CheckboxMenuItem makeCheckboxMenuItem(String label, 
                        ItemListener l, String name) {
                CheckboxMenuItem ci = new CheckboxMenuItem(label) ;
                ci.setName(name) ;
                ci.addItemListener(l) ;
                return ci ;
        }

        // ---- method, adapter class to construct submenus ----
        // ---- for secondary menu ----

        Menu makeEnableDisableMenu(Menu m, boolean enable, 
                        String label) {
                Menu msub = new Menu(label) ;
                for (int i = 0 ; i < m.getItemCount() ; i++) {
                        MenuItem mi = m.getItem(i) ;
                        msub.add(makeMenuItem(mi.getLabel(),
                                new EnabledAdapter(mi, enable)) ) ;
                }
                return msub ;
        }

        class EnabledAdapter implements ActionListener {

                MenuItem target ;
                boolean enable ;

                EnabledAdapter(MenuItem t, boolean e) {
                        target = t ;
                        enable = e ;
                }

                public void actionPerformed(ActionEvent e) {
                        target.setEnabled(enable) ;
                        String which = 
                                (enable ? "enabling" : "disabling") ;
                        display.setText(which + " item labeled " +
                                target.getLabel() ) ;
                }
        }

        // sets text for display.
        void setDisplay(String s) {
                display.setText(s) ;
        }

        // "processes" regular menu item (displays its action command).
        void processCommand(String cmd) {
                display.setText("processing " + cmd + " command") ;
        }

        // "processes" checkbox menu item (displays its state).
        void processCheck(CheckboxMenuItem c) {
                String onOff = (c.getState() ? "on" : "off") ;
                display.setText("setting " + c.getName() + 
                        " checkbox " + onOff) ;
        }

        //
        // ---- main ---------------------------------------------------
        //
        // no command-line arguments.
        //
        public static void main(String[] args) {

                MenuExample m = new MenuExample() ;
        }
}