Question

From Coderanch and Sun Forum, I know the technique to have a horizontal scroll bar for JComboBox.

However, their suggested solution are bounded to Look n Feel specific.

As you can see, the below key code snippet will not work well, if users are under Linux machine with GTK+ look n feel, or Windows machine with Nimbus look n feel.

How I can have a portable way, to make JComboBox able to have a horizontal scroll bar?

The complete source code is AutoCompleteJComboBox.java

The key code snippet are as follow :

package org.yccheok.jstock.gui;

public class AutoCompleteJComboBox extends JComboBox {

   @Override
    public void setUI(ComboBoxUI ui)
    {
        if (ui != null)
        {
            // Let's try our own customized UI.
            Class c = ui.getClass();
            final String myClass = "org.yccheok.jstock.gui.AutoCompleteJComboBox$My" + c.getSimpleName();

            try {
                ComboBoxUI myUI = (ComboBoxUI) Class.forName(myClass).newInstance();
                super.setUI(myUI);
                return;
            } catch (ClassNotFoundException ex) {
                log.error(null, ex);
            } catch (InstantiationException ex) {
                log.error(null, ex);
            } catch (IllegalAccessException ex) {
                log.error(null, ex);
            }
        }

        // Either null, or we fail to use our own customized UI.
        // Fall back to default.
        super.setUI(ui);
    }

    // This is a non-portable method to make combo box horizontal scroll bar.
    // Whenever there is a new look-n-feel, we need to manually provide the ComboBoxUI.
    // Any idea on how to make this portable?
    //
    protected static class MyWindowsComboBoxUI extends com.sun.java.swing.plaf.windows.WindowsComboBoxUI
    {
        @Override
        protected ComboPopup createPopup()
        {
            return new MyComboPopup(comboBox);
        }
    }

    protected static class MyMotifComboBoxUI extends com.sun.java.swing.plaf.motif.MotifComboBoxUI
    {
        @Override
        protected ComboPopup createPopup()
        {
            return new MyComboPopup(comboBox);
        }
    }

    protected static class MyMetalComboBoxUI extends javax.swing.plaf.metal.MetalComboBoxUI
    {
        @Override
        protected ComboPopup createPopup()
        {
            return new MyComboPopup(comboBox);
        }
    }

    private static class MyComboPopup extends BasicComboPopup
    {
        public MyComboPopup(JComboBox combo)
        {
            super(combo);
        }

        @Override
        public JScrollPane createScroller()
        {
            return new JScrollPane(list,JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                    JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
        }
    }
}

Answer 1

I got my problem resolved through the following forum
Oracle Java Swing Forum