Αντικειμενοστραφής Προγραμματισμός

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====== CheckBox Menu Items & RadioButton Menu Items ======

Σε αναλογία με τα check box buttons και radio buttons μπορείτε να ορίσετε σε ένα μενού //CheckBox Menu Items// και //RadioButton Menu Items//. Δείτε το παρακάτω παράδειγμα χρήσης ενός τέτοιου μενού από το [[https://docs.oracle.com/javase/tutorial/uiswing/components/menu.html|site της Oracle]].

Για την εκτέλεση του παρακάτω κώδικα θα χρειαστείτε το εικονίδιο [[https://docs.oracle.com/javase/tutorial/uiswing/examples/components/MenuLookDemoProject/src/components/images/middle.gif|middle.gif]].

<code java MenuLookDemo.java>
import java.awt.*;
import java.awt.event.*;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JCheckBoxMenuItem;
import javax.swing.JRadioButtonMenuItem;
import javax.swing.ButtonGroup;
import javax.swing.JMenuBar;
import javax.swing.KeyStroke;
import javax.swing.ImageIcon;

import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JFrame;

/* MenuLookDemo.java requires middle.gif. */

/*
 * This class exists solely to show you what menus look like.
 * It has no menu-related event handling.
 */
public class MenuLookDemo {
  JTextArea output;
  JScrollPane scrollPane;

  public JMenuBar createMenuBar() {
    JMenuBar menuBar;
    JMenu menu, submenu;
    JMenuItem menuItem;
    JRadioButtonMenuItem rbMenuItem;
    JCheckBoxMenuItem cbMenuItem;

    //Create the menu bar.
    menuBar = new JMenuBar();

    //Build the first menu.
    menu = new JMenu("A Menu");
    menu.setMnemonic(KeyEvent.VK_A);
    menu.getAccessibleContext().setAccessibleDescription(
        "The only menu in this program that has menu items");
    menuBar.add(menu);

    //a group of JMenuItems
    menuItem = new JMenuItem("A text-only menu item",
                 KeyEvent.VK_T);
    //menuItem.setMnemonic(KeyEvent.VK_T); //used constructor instead
    menuItem.setAccelerator(KeyStroke.getKeyStroke(
        KeyEvent.VK_1, ActionEvent.ALT_MASK));
    menuItem.getAccessibleContext().setAccessibleDescription(
        "This doesn't really do anything");
    menu.add(menuItem);

    ImageIcon icon = createImageIcon("middle.gif");
    menuItem = new JMenuItem("Both text and icon", icon);
    menuItem.setMnemonic(KeyEvent.VK_B);
    menu.add(menuItem);

    menuItem = new JMenuItem(icon);
    menuItem.setMnemonic(KeyEvent.VK_D);
    menu.add(menuItem);

    //a group of radio button menu items
    menu.addSeparator();
    ButtonGroup group = new ButtonGroup();

    rbMenuItem = new JRadioButtonMenuItem("A radio button menu item");
    rbMenuItem.setSelected(true);
    rbMenuItem.setMnemonic(KeyEvent.VK_R);
    group.add(rbMenuItem);
    menu.add(rbMenuItem);

    rbMenuItem = new JRadioButtonMenuItem("Another one");
    rbMenuItem.setMnemonic(KeyEvent.VK_O);
    group.add(rbMenuItem);
    menu.add(rbMenuItem);

    //a group of check box menu items
    menu.addSeparator();
    cbMenuItem = new JCheckBoxMenuItem("A check box menu item");
    cbMenuItem.setMnemonic(KeyEvent.VK_C);
    menu.add(cbMenuItem);

    cbMenuItem = new JCheckBoxMenuItem("Another one");
    cbMenuItem.setMnemonic(KeyEvent.VK_H);
    menu.add(cbMenuItem);

    //a submenu
    menu.addSeparator();
    submenu = new JMenu("A submenu");
    submenu.setMnemonic(KeyEvent.VK_S);

    menuItem = new JMenuItem("An item in the submenu");
    menuItem.setAccelerator(KeyStroke.getKeyStroke(
        KeyEvent.VK_2, ActionEvent.ALT_MASK));
    submenu.add(menuItem);

    menuItem = new JMenuItem("Another item");
    submenu.add(menuItem);
    menu.add(submenu);

    //Build second menu in the menu bar.
    menu = new JMenu("Another Menu");
    menu.setMnemonic(KeyEvent.VK_N);
    menu.getAccessibleContext().setAccessibleDescription(
        "This menu does nothing");
    menuBar.add(menu);

    return menuBar;
  }

  public Container createContentPane() {
    //Create the content-pane-to-be.
    JPanel contentPane = new JPanel(new BorderLayout());
    contentPane.setOpaque(true);

    //Create a scrolled text area.
    output = new JTextArea(5, 30);
    output.setEditable(true);
    scrollPane = new JScrollPane(output);

    //Add the text area to the content pane.
    contentPane.add(scrollPane, BorderLayout.CENTER);

    return contentPane;
  }

  /** Returns an ImageIcon, or null if the path was invalid. */
  protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = MenuLookDemo.class.getResource(path);
    if (imgURL != null) {
      return new ImageIcon(imgURL);
    } else {
      System.err.println("Couldn't find file: " + path);
      return null;
    }
  }

  /**
   * Create the GUI and show it.  For thread safety,
   * this method should be invoked from the
   * event-dispatching thread.
   */
  private static void createAndShowGUI() {
    //Create and set up the window.
    JFrame frame = new JFrame("MenuLookDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Create and set up the content pane.
    MenuLookDemo demo = new MenuLookDemo();
    frame.setJMenuBar(demo.createMenuBar());
    frame.setContentPane(demo.createContentPane());

    //Display the window.
    frame.setSize(450, 260);
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    //Schedule a job for the event-dispatching thread:
    //creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}
</code>