Why is Look and Feel not calling my ButtonUI?

[Robert Paris]

I created a LookAndFeel class that extends the MetalLookAndFeel. The only thing it really overrides is the ButtonUI. It does the following:

protected void initClassDefaults(UIDefaults table) 
{
super.initClassDefaults(table);
Object[] uiDefaults = { "ButtonUI", "com.mycompany.plaf.ButtonUI" };
table.putDefaults( uiDefaults );
}

Then in the ButtonUI class, I have a "System.out.println" in every method, yet nothing prints out. Any idea what's wrong?

[Nathan Pruett]

Did you remember to implement a "public static ComponentUI createUI( JComponent c )" method in your class? Check out the JavaDoc on this method... you have to implement it in every ComponentUI subclass for it to get installed correctly.

[Robert Paris]

yes, I have:

private final static MyButtonUI buttonUI = new MyButtonUI();
publis static ComponentUI createUI(JComponent c)
{
     return buttonUI;
}
  

[Robert Paris]

Is the problem one of loading? I have the look and feel classes on the classpath - should they be in the extensions (ext) folder?

[Robert Paris]

OK, it's not the loading issue. I put it in the ext folder and it still didn't work. Here's what's weird though:
When I explicitly called jbutton.setUI( ( ButtonUI ) MyButtonUI.createUI( jbutton ) ) it worked! The button took my class, appeared properly and all the system.out's printed! Argh! So why is the LookAndFeel not properly installing it? Any ideas what I'm doing wrong?

[Nathan Pruett]

OK... are you telling the application that you want to use your look and feel?

    public static void main( String[] args ) {
        try {
            UIManager.setLookAndFeel( new com.mycompany.plaf.MyPlaf() );
        }
        catch (UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }
        .
        .
        .

You can also tell Java to make your look and feel the default... make a swing.properties file in your $JAVA_HOME/jre/lib directory, put the following line in it -

swing.defaultlaf=com.mycompany.plaf.MyPlaf

And make sure your classes are on the default classpath (or ext directory).

[Robert Paris]

Thanks for the reply.
Yes, it is definitely installing my look and feel class because it returns the name of my L&F class when I do:

System.out.println( UIManager.getLookAndFeel().getName() );

HOWEVER, when I do the following, it returns the metal look and feel class:

//RETURNS METAL CLASS, NOT MY L&F BUTTON CLASS
System.out.println( myButton.getUI().getClass() );

What's weird is the look and feel class I have seems to be ok, because the following code installs it for the button:

//THIS INSTALLS THE CORRECT L&F FOR THIS BUTTON
myButton.setUI( (javax.swing.plaf.ButtonUI)com.mine.MyButtonUI.createUI( myButton ) );

Any idea what's wrong?

[Nathan Pruett]

Here's the (really barebones) test code I've made to test stuff out, and it's working...

The ButtonUI class :

package com.mycompany.plaf;
 
import java.awt.Color;
import java.awt.Graphics;
 
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.SwingUtilities;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.metal.MetalButtonUI;
  
public class ButtonUI extends MetalButtonUI {
    
    private final static ButtonUI buttonUI = new ButtonUI();
    
    public void paint(Graphics g, JComponent c) {
        System.out.println( "HERE!" );
        JButton b = (JButton)c;
        System.out.println( b.getText() );
        g.setColor( Color.red );
        g.fill3DRect( 0, 0, c.getWidth(), c.getHeight(), !b.getModel().isPressed() );
        g.setColor( c.getForeground() );
        g.drawString( b.getText(), 
                (c.getWidth() - SwingUtilities.computeStringWidth( g.getFontMetrics(), 
                 b.getText() ) ) / 2, 
                 ( c.getHeight() + g.getFontMetrics().getAscent() ) / 2 );
    }
    
    public static ComponentUI createUI(JComponent c)
    {
        return buttonUI;
    }
}

The MyPlaf class :

package com.mycompany.plaf;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIDefaults;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.plaf.metal.MetalLookAndFeel;
  
public class MyPlaf extends MetalLookAndFeel {
    protected void initClassDefaults(UIDefaults table) 
    {
        super.initClassDefaults(table);
        table.put( "ButtonUI", "com.mycompany.plaf.ButtonUI" );
    }
    
    public static void main( String[] args ) {
        try {
            UIManager.setLookAndFeel( new MyPlaf() );
        }
        catch (UnsupportedLookAndFeelException e) {
            e.printStackTrace();
        }
        
        JFrame f = new JFrame();
        JPanel p = new JPanel();
        JButton b = new JButton( "Test" );
        System.out.println( b.getUI().getClass().toString() );
        p.add( b );
        f.getContentPane().add( p );
        f.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        f.setSize( 300, 300 );
        f.setLocationRelativeTo( null );
        SwingUtilities.updateComponentTreeUI( f );
        f.setVisible( true );
    }
}

[ January 28, 2004: Message edited by: Nathan Pruett ]

[Robert Paris]

Thanks!! It works. The problem was that I wasn't implementing paint(). All the java.sun.com tutorials never mentioned implementing paint(), but if you don't, it won't use your button UI. I had only implemented update() instead of paint (and let it use MetalButtonUI's paint method) and for some reason that kept it from using my UI.