Need some info on menus

[ddmeightball]

I am interested in learning how to do drop down menus in my Java GUI's. I just need some information before i get started

What classes are needing for drop down menus? How does Java respond to a menu selection? Does it use a ListSelectionListener or an ActionEventListener?

Can I see a very simple example of a drop down menu.

[System_Error]

If you use Swing, which is what I would recommend, use JComboBox:

JComboBox jcb = new JComboBox();
jcb.addActionListener(this);


then to add stuff to it:

jcb.addItem("One");
jcb.addItem("Two");


in the actionPeformed method:
I would do this:

	String strWhich = (String)jcb.getSelectedItem();

if (strWhich  == "One")
{
   //do something
}

I do have an example from a while back that converts currency, let me know if your interested in seeing it.

[manavo11]

Do you mean a combo box or a menu? Here is an example if a menu is what you want :

import java.awt.*;
import java.awt.event.*;

public class TestMenu extends Frame {//implements ActionListener{

	public static void main(String args[]) {
		TestMenu T=new TestMenu("Window title");
		T.pack();
		T.show();
	}

	public TestMenu(String title) {
		super(title);

		setLayout(new BorderLayout());

		Button bAdd=new Button("Button");
		add(bAdd);

		FileMenu fileMenu = new FileMenu(this);

		MenuBar mb = new MenuBar();
		mb.add(fileMenu);
		setMenuBar(mb);

		addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e) {
				System.exit(0);
			}
		});
	}

    public void exit() {
		setVisible(false);
		dispose();
		System.exit(0);
	}

}

class FileMenu extends Menu implements ActionListener {
  TestMenu TM;  // who owns us?
  public FileMenu(TestMenu tm) {
    super("File");
    TM = tm;
    MenuItem mi;
    add(mi = new MenuItem("Exit"));
    mi.addActionListener(this);
  }

  public void actionPerformed(ActionEvent e) {
    String item = e.getActionCommand();
    if (item.equals("Exit")) {
		TM.exit();
    } else {
      System.out.println("Selected FileMenu " + item);
	}
  }
}

[System_Error]

Maybe that's what he meant!

[nebulom]

Just for addition to Phillip's post. You can do it like this on swing

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
public class test extends JFrame{
    JMenuBar mbar=new JMenuBar();
    JMenu mnufile=new JMenu("File");
    JMenuItem mnuexit=new JMenuItem("Exit");
    public test(){
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setSize(300,300);
 
        setJMenuBar(mbar);
        mbar.add(mnufile);
        mnufile.add(mnuexit);
 
        mnuexit.addActionListener(new ActionListener(){
            public void actionPerformed(ActionEvent e){
                mnuexit_actionPerformed(e);
            }
        });
    }
    void mnuexit_actionPerformed(ActionEvent e){
        System.exit(0);
    }
 
    public static void main(String[] args){
        new test().setVisible(true);
    }
}

Btw, show is deprecated, so refrain from using it. Also I created the mnuexit_actionPerformed on the class' scope. This is just for some use. You can access it from within the class.

[ddmeightball]

I wanted a menu, not a combo box. Kinda like the menu that we all have in our internet browsers. you know, FILE, EDIT, VIEW, etc.

[ddmeightball]

Ok, i was tinkering around with this and I wanted to just make an ActionPerformed method, not an abstract method. The problem comes up when i try to add the actionlistener to my exit JMenuItem.

mnuexit.addActionListener(this);

I get this error

addActionListener(java.awt.event.ActionListener) in javax.swing.AbstractButton cannot be applied to (TestMenu2)

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TestMenu2 extends JFrame{
	JMenuBar mbar=new JMenuBar();//creates the menu bar
	
	JMenu mnufile=new JMenu("File");//creates the file selection of the menu bar
	JMenuItem mnuexit=new JMenuItem("Exit");//creates the options for the file menu

	JMenu mnuEdit = new JMenu("Edit");//create the edit selection of the menu bar
	JMenuItem mnuCopy=new JMenuItem("Copy");//creates the options for the file menu

	
	public TestMenu2(){
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setSize(300,300);

		setJMenuBar(mbar);
		mbar.add(mnufile);//adds "File"
		mnufile.add(mnuexit);//adds "Exit" option for the file selection
		
		mbar.add(mnuEdit);//adds "Edit"
		mnuEdit.add(mnuCopy);//adds copy to Edit

		mnuexit.addActionListener(this);
	}
	
	public void actionPerformed(ActionEvent e){
		if(e.getSource()=="Exit"){
			System.exit(0);		
		}
	}

	public static void main(String[] args){
		new TestMenu2().setVisible(true);
	}
}

[System_Error]

you didn't implement the actionListener?