Java JComboBox Custom Renderer and GTK

Answer 1

The DefaultListCellRenderer extends JLabel and looks like JLabel. If you have non-editable ComboBox then Renderer returned via getRenderer is used for painting drop down list area and also for "input" area. Try to play with border/foreground/background settings for ComboBox and renderer.

Answer 2

Try this:

public Component getListCellRendererComponent(
        JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
    if (value instanceof Customer) {
        Customer c = (Customer) value;

        StringBuffer sb = new StringBuffer();
        if (c.getCompany() != null && c.getCompany().length() > 0) {
            sb.append(c.getCompany());
        }
        sb.append(" - ");
        if (c.getCompany() != null && c.getCompany().length() > 0) {
            sb.append(c.getContact());
        }
        sb.append(" - ");
        if (c.getCompany() != null && c.getCompany().length() > 0) {
            sb.append(c.getCity());
            sb.append(", ");
        }            
        if (c.getCompany() != null && c.getCompany().length() > 0) {
            sb.append(c.getState());
        }

        value = sb.toString();
    } 
    return super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
  }
}

Also use a StringBuilder not a StringBuffer (this is a single threaded situation).

Also also it looks like you have cut and paste errors in the code for instance:

        if (c.getCompany() != null && c.getCompany().length() > 0) {
            sb.append(c.getState());
        }

Is checking the Company member and using the State member.

Answer 3

Same issue, I did this in order to customize it for showing icons:

private static class CustomComboBoxRenderer extends DefaultListCellRenderer
{
    private final ListCellRenderer backend;

    public CustomComboBoxRenderer(ListCellRenderer backend)
    {
        this.backend = backend;
    }

    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus)
    {
        Component component = backend.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
        if(component instanceof JLabel == false)
            component = super.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
        JLabel label = (JLabel)component;
        label.setIcon(Icons.COMPONENT);
        return label;
    }
}

Then assigned the renderer like this:

comboBox.setRenderer(new CustomComboBoxRenderer(comboBox.getRenderer()));

This has worked out fine for me, so far.