Re: [JmenuItem] menuItem when clicking on menu item

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.help
Date:
Sun, 28 Dec 2008 22:52:21 -0800
Message-ID:
<495873a5$0$23142$b9f67a60@news.newsdemon.com>
John B. Matthews wrote:

In article <4958486d$0$23155$b9f67a60@news.newsdemon.com>,
 Knute Johnson <nospam@rabbitbrush.frazmtn.com> wrote:

Daniel Moyne wrote:

I have created the same ActionListener on a collection of menu items in a
loop like this :
for (int i = 0; i < NUMBER_OPENED_FILES + 1; i++) {
name =.....
menuItem = new JMenuItem(name);
menuItem.setName("menuItem_" + String.valueOf(i));
menuItem.addActionListener(new java.awt.event.ActionListener() {
    public void actionPerformed(java.awt.event.ActionEvent evt) {
 menuItemActionPerformed(evt);
}
 });
}

In my method actionPerformed I want to know which menu has been
clicked; I know it is ridiculous because normally :
(1) you attach an ActionListener at each menu item,
(2) and in general you do not care about the menu item clicked.

I can process the string evt to extract the identifier of the menu item
clicked as the desired information in recorded in evt ; any other ideas ?

[...]
You can override JMenuItem to include a index number (the OO folks will
cringe though) or you can put them in an ArrayList and get their index
that way. The latter is probably best.


Knute's right, but I couldn't resist trying this alternative:

<code>
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.io.File;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

/**
 * @author John B. Matthews
 */
public class FileMenu {

     public static void main(String[] args) {

         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 (new FileMenu()).create();
             }
         });
     }

     void create() {
         File userDir = new File(System.getProperty("user.dir"));
         File[] files = userDir.listFiles();

         JMenu menu = new JMenu("Recent Files");
         for (File f : files) {
             if (f.isFile()) {
                 RecentFile rf = new RecentFile(f);
                 menu.add(new JMenuItem(rf.getAction()));
             }
         }
         JMenuBar bar = new JMenuBar();
         bar.add(menu);
         
         JFrame f = new JFrame("FileMenu");
         f.setJMenuBar(bar);
         f.pack();
         f.setSize(480, 320);
         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         f.setLocationRelativeTo(null);
         f.setVisible(true);
     }
}

class RecentFile {

    private final File file;
    private final Action action;

    public RecentFile(final File file) {
        this.file = file;
        this.action = new AbstractAction(file.getPath()) {
            public void actionPerformed(ActionEvent ae) {
                System.out.println(file.length()
                    + " " + file.getAbsolutePath());
            }
        };
    }

    public Action getAction() {
        return action;
    }
}
</code>


I like that, even more OO, if such can be said.

--

Knute Johnson
email s/nospam/knute2008/

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