Submenus, checkbox menu items, swapping menus,mnemonics (shortcuts) and action commands
// : c14:SwingMenus.java
// Submenus, checkbox menu items, swapping menus,
// mnemonics (shortcuts) and action commands.
// <applet code=SwingMenus width=300 height=100></applet>
// From 'Thinking in Java, 3rd ed.' (c) Bruce Eckel 2002
// www.BruceEckel.com. See copyright notice in CopyRight.txt.
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
import javax.swing.JApplet;
import javax.swing.JButton;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JTextField;
public class SwingMenus extends JApplet {
private String[] flavors = { "Chocolate", "Strawberry",
"Vanilla Fudge Swirl", "Mint Chip", "Mocha Almond Fudge",
"Rum Raisin", "Praline Cream", "Mud Pie" };
private JTextField t = new JTextField("No flavor", 30);
private JMenuBar mb1 = new JMenuBar();
private JMenu f = new JMenu("File"), m = new JMenu("Flavors"),
s = new JMenu("Safety");
// Alternative approach:
private JCheckBoxMenuItem[] safety = { new JCheckBoxMenuItem("Guard"),
new JCheckBoxMenuItem("Hide") };
private JMenuItem[] file = { new JMenuItem("Open") };
// A second menu bar to swap to:
private JMenuBar mb2 = new JMenuBar();
private JMenu fooBar = new JMenu("fooBar");
private JMenuItem[] other = {
// Adding a menu shortcut (mnemonic) is very
// simple, but only JMenuItems can have them
// in their constructors:
new JMenuItem("Foo", KeyEvent.VK_F),
new JMenuItem("Bar", KeyEvent.VK_A),
// No shortcut:
new JMenuItem("Baz"), };
private JButton b = new JButton("Swap Menus");
class BL implements ActionListener {
public void actionPerformed(ActionEvent e) {
JMenuBar m = getJMenuBar();
setJMenuBar(m == mb1 ? mb2 : mb1);
validate(); // Refresh the frame
}
}
class ML implements ActionListener {
public void actionPerformed(ActionEvent e) {
JMenuItem target = (JMenuItem) e.getSource();
String actionCommand = target.getActionCommand();
if (actionCommand.equals("Open")) {
String s = t.getText();
boolean chosen = false;
for (int i = 0; i < flavors.length; i++)
if (s.equals(flavors[i]))
chosen = true;
if (!chosen)
t.setText("Choose a flavor first!");
else
t.setText("Opening " + s + ". Mmm, mm!");
}
}
}
class FL implements ActionListener {
public void actionPerformed(ActionEvent e) {
JMenuItem target = (JMenuItem) e.getSource();
t.setText(target.getText());
}
}
// Alternatively, you can create a different
// class for each different MenuItem. Then you
// Don't have to figure out which one it is:
class FooL implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText("Foo selected");
}
}
class BarL implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText("Bar selected");
}
}
class BazL implements ActionListener {
public void actionPerformed(ActionEvent e) {
t.setText("Baz selected");
}
}
class CMIL implements ItemListener {
public void itemStateChanged(ItemEvent e) {
JCheckBoxMenuItem target = (JCheckBoxMenuItem) e.getSource();
String actionCommand = target.getActionCommand();
if (actionCommand.equals("Guard"))
t.setText("Guard the Ice Cream! " + "Guarding is "
+ target.getState());
else if (actionCommand.equals("Hide"))
t.setText("Hide the Ice Cream! " + "Is it hidden? "
+ target.getState());
}
}
public void init() {
ML ml = new ML();
CMIL cmil = new CMIL();
safety[0].setActionCommand("Guard");
safety[0].setMnemonic(KeyEvent.VK_G);
safety[0].addItemListener(cmil);
safety[1].setActionCommand("Hide");
safety[1].setMnemonic(KeyEvent.VK_H);
safety[1].addItemListener(cmil);
other[0].addActionListener(new FooL());
other[1].addActionListener(new BarL());
other[2].addActionListener(new BazL());
FL fl = new FL();
for (int i = 0; i < flavors.length; i++) {
JMenuItem mi = new JMenuItem(flavors[i]);
mi.addActionListener(fl);
m.add(mi);
// Add separators at intervals:
if ((i + 1) % 3 == 0)
m.addSeparator();
}
for (int i = 0; i < safety.length; i++)
s.add(safety[i]);
s.setMnemonic(KeyEvent.VK_A);
f.add(s);
f.setMnemonic(KeyEvent.VK_F);
for (int i = 0; i < file.length; i++) {
file[i].addActionListener(fl);
f.add(file[i]);
}
mb1.add(f);
mb1.add(m);
setJMenuBar(mb1);
t.setEditable(false);
Container cp = getContentPane();
cp.add(t, BorderLayout.CENTER);
// Set up the system for swapping menus:
b.addActionListener(new BL());
b.setMnemonic(KeyEvent.VK_S);
cp.add(b, BorderLayout.NORTH);
for (int i = 0; i < other.length; i++)
fooBar.add(other[i]);
fooBar.setMnemonic(KeyEvent.VK_B);
mb2.add(fooBar);
}
public static void main(String[] args) {
run(new SwingMenus(), 300, 100);
}
public static void run(JApplet applet, int width, int height) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(applet);
frame.setSize(width, height);
applet.init();
applet.start();
frame.setVisible(true);
}
} ///:~
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