Re: Combobox Project: How to put 4 text items in the combobox

From:

Knute Johnson <nospam@knutejohnson.com>

Newsgroups:

comp.lang.java.programmer

Date:

Wed, 10 Oct 2012 13:31:52 -0700

Message-ID:

<k54lvo$9pj$1@dont-email.me>

On 10/10/2012 12:41 PM, christopher.m.lusardi@gmail.com wrote:

How do I change the below project, so that it has the following text as the 4 items of the combobox: Apples, Cars, Shrimp, Moon.

package colorcomboboxeditor;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ComboBoxEditor;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.event.EventListenerList;

class ColorComboBoxEditor implements ComboBoxEditor
{
     final protected JButton editor;
     protected EventListenerList listenerList = new EventListenerList();

     public ColorComboBoxEditor(Color initialColor)
     {
         editor = new JButton("");
         editor.setBackground(initialColor);

         ActionListener actionListener = new ActionListener()
         {
             public void actionPerformed(ActionEvent e)
             {
                 Color currentBackground = editor.getBackground();
                 Color color = JColorChooser.showDialog(editor, "Color Chooser", currentBackground);

The code below is problematic as it won't compare whether
currentBackground is the same color, only if it is the same Object. You
must use the Color.equals() method to determine equality.

                 if ( (color != null) && (currentBackground != color) )
                 {
                     editor.setBackground(color);
                     fireActionEvent(color);
                 }
             }
         };

         editor.addActionListener(actionListener);
     }

     public void addActionListener(ActionListener l)
     {
         listenerList.add(ActionListener.class, l);
     }

     public Component getEditorComponent()
     {
         return editor;
     }

     public Object getItem()
     {
         return editor.getBackground();
     }

     public void removeActionListener(ActionListener l)
     {
         listenerList.remove(ActionListener.class, l);
     }

     public void selectAll()
     {
         // Ignore
     }

     public void setItem(Object newValue)
     {
         if ( newValue instanceof Color )
         {
             Color color = (Color) newValue;
             editor.setBackground(color);

The code above is redundant. Just say;

editor.setBackground(newValue);

         }
         else
         {
             try
             {
                 Color color = Color.decode(newValue.toString());
                 editor.setBackground(color);
             }
             catch (NumberFormatException e)
             {
             }
         }
     }

     protected void fireActionEvent(Color color)
     {
         Object listeners[] = listenerList.getListenerList();

         for (int i = listeners.length - 2; i >= 0; i -= 2)
         {
             if ( listeners[i] == ActionListener.class )
             {
                 ActionEvent actionEvent = new ActionEvent(editor, ActionEvent.ACTION_PERFORMED, color.toString());
                 ((ActionListener) listeners[i + 1]).actionPerformed(actionEvent);
             }
         }
     }
}

//-----------
/*
  * To change this template, choose Tools | Templates
  * and open the template in the editor.
  */
package colorcomboboxeditor;

import java.awt.BorderLayout;
import java.awt.Color;
import javax.swing.JComboBox;
import javax.swing.JFrame;

public class ColorComboBoxEditorDemo
{

     public static void main(String args[])
     {
         Color colors[] = {Color.WHITE, Color.BLACK, Color.RED, Color.BLUE};

You change the line above to be the list of items you want in the combo box.

All Swing GUI creation code must be run on the Event Dispatch Thread
(EDT). To do that you need to put the code below inside of;

EventQueue.invokeLater(new Runnable() {
public void run() {

         JFrame frame = new JFrame("Editable JComboBox");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         final JComboBox comboBox = new JComboBox(colors);
         comboBox.setEditable(true);
         comboBox.setEditor(new ColorComboBoxEditor(Color.RED));
         frame.add(comboBox, BorderLayout.NORTH);

         frame.setSize(300, 100);
         frame.setVisible(true);
     }

}
});

}

It really isn't clear what you are trying to do. Do you want to be able
to add colors to the JComboBox or do you want them to have some obscured
name?

--

Knute Johnson