How can I render a JList cell with JCheckBox?

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MaoXuePeng - 14 Oct 2004 13:27 GMT

I do it like this:

public class CheckBoxCellRenderer extends JCheckBox implements
ListCellRenderer {

public CheckBoxCellRenderer() {
super();
}
public Component getListCellRendererComponent(JList list, Object value,
int index, boolean isSelected, boolean cellHasFocus) {

if(isSelected)
{
this.setForeground(java.awt.Color.BLUE);

}
this.setEnabled(isSelected);
this.setText("Hello");
return this;
}

However, there is a problem: I can not select or disselect those check
box
rendered in the JList.
What wrong?

Thanks.
MaoXuePeng.

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Babu Kalakrishnan - 14 Oct 2004 13:53 GMT

> I do it like this:
>
[quoted text clipped - 21 lines]
> rendered in the JList.
> What wrong?

Not clear what you're trying to achieve.

A Renderer is a component that is never really "present" in the
component hierarchy. When the list is being painted, the renderer is
added temporarily (not even directly - but that's an implementtion
issue) , placed at the appropriate location, is asked to paint itself,
and removed immediately thereafter. So what you see on screen is not
really the component itself - but just what it painted. You cannot
therefore expect it to react to user inputs and change state.

If what you want is an editable JList with a JCheckbox as the editor,
use a JTable with a single column, and use a JCheckBox as its
*CellEditor* (not Renderer).

BK

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MaoXuePeng - 14 Oct 2004 14:31 GMT

Thank you,BK.

I want to make the check box which rendered on the JList editable, but
failed.

> So what you see on screen is not
> really the component itself - but just what it painted. > You cannot
> therefore expect it to react to user inputs and change
> state.
> If what you want is an editable JList with a JCheckbox as > the editor,

> use a JTable with a single column, and use a JCheckBox as > its
> *CellEditor* (not Renderer).

I think you are right. I am to try it and post the answer later.

Regards!
MaoXuePeng.

Reply to this Message

Andrew Thompson - 14 Oct 2004 14:02 GMT

> I do it like this:

The 'tame' swing examples has a version that works as you want.
<http://www.physci.org/codes/tame/>

Follow the links to the launcher applet and check 'CheckListExample'
and 'CheckListExample2' to see them, follow the 'Launchet' link
from the top of the page, the drop-down menu shows the source.

HTH

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How can I render a JList cell with JCheckBox?

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