Can I put JLabel array in JComboBox?

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niceguy16 - 27 Apr 2006 04:32 GMT

Here is the code. It runs but does not display the labels. Why?

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

public class Combo implements ActionListener{
    JComboBox comboBox;
    JLabel i= new JLabel();
    JLabel[] items = new JLabel[4];
public static void main(String[] args) {
JFrame f = new JFrame("Interest Rate");
Combo c=new Combo();
f.setSize(300, 200);
f.setLocation(200, 200);
Container pane = f.getContentPane();
c.items[0] = new JLabel("5.25");
    c.items[1] = new JLabel("5.5");
    c.items[2] = new JLabel("5.75");
c.items[3] = new JLabel("6.0");
c.create();
c.comboBox.setEditable(true);
    BorderLayout brd = new BorderLayout();
    pane.setLayout(brd);
    pane.add(c.comboBox,BorderLayout.NORTH);
    pane.add(c.items[0],BorderLayout.CENTER);
    pane.add(c.i, BorderLayout.SOUTH);
f.setVisible(true);
}

public void actionPerformed(ActionEvent ae) {
    Object selection = comboBox.getSelectedItem();
i.setText("User has selected interest rate " + selection + "%");
}

private void create(){
comboBox = new JComboBox(items);
comboBox.addActionListener(this);
}}

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Bart Cremers - 27 Apr 2006 06:44 GMT

Of course you can, although I don't see the use for it in your example.
The default renderers and editors for a JComboBox are designed to work
with Strings and primite wrappers, so in your example it would be
better to add an array of Double objects to the combobox:

Double[] items = new Double[4];

...

c.intems[0] = new Double(5.25);
...
pane.add(new JLabel(c.items[0].toString()), BorderLayout.CENTER);
...

This should render perfectly.

If you want for some obscure want to add an array of JLabels you'll
have to override the renderer (c.comboBox.setRenderer(subclass of
DefaultListCellRenderer). More work is involved even if you want the
combobox also to be editable. This requires you to set the editor on
the combobox (c.combBox.setEditor(implementation of ComboBoxEditor). As
you can see a lot of work while you probable gain nothing from it.

Bart

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Vova Reznik - 27 Apr 2006 14:48 GMT

> Here is the code. It runs but does not display the labels. Why?
>
[quoted text clipped - 35 lines]
> comboBox.addActionListener(this);
> }}

Because combo box renderer uses toString() to show.
You may write your own version of JLabel where
toString() will return text:

public String toString() {
return getText();
}

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Can I put JLabel array in JComboBox?

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