Setting the Look and Feel only if not changed by the user

I came up with a solution that seems to be working well for me.  I prefer that the users rely on the Options panel to change the Look and Feel.  I created the following class and then I call it in my installer class passing in the default L&F I want to use in that application.  I also pass in the Dark Nimbus L&F as an extra L&F to support.


Code:

public class LookAndFeelUtility {

    // force the user to use the constructor that requires a default look and feel.
    private LookAndFeelUtility() {
        defaultLookAndFeel = null;
        extraLookAndFeels = new HashSet<>();
    }

    /**
     * Creates an instance of the LookAndFeelUtility
     *
     * @param defaultLookAndFeel this is the default look and feel that will be
     * used if this is the first installation and initial launch of the application.
     */
    public LookAndFeelUtility(LookAndFeel defaultLookAndFeel) {
        this.defaultLookAndFeel = defaultLookAndFeel;
        extraLookAndFeels = new HashSet<>();
    }

    public void addExtraLookAndFeel(LookAndFeel extraLookAndFeel) {
        extraLookAndFeels.add(extraLookAndFeel);
    }

    private final HashSet<LookAndFeel> extraLookAndFeels;
    private final LookAndFeel defaultLookAndFeel;

    private Preferences getPreferences() {
        return NbPreferences.root().node("laf");
    }

    /**
     * This will set the look and feel according to what was saved by the application
     * from the previous execution; otherwise it will use the default look and feel
     * passed to the constructor.
     */
    public void setLookAndFeel() {
        LookAndFeel lookAndFeel = null;

        Preferences prefs = getPreferences();
        boolean firstTime = prefs.getBoolean("first_launch", true);  // used to know if this is the first launch after initial installation of the application.
        String lookAndFeelClassStr = prefs.get("laf", "na");
        if (firstTime) {
            prefs.put("laf", defaultLookAndFeel.getClass().getTypeName());
            lookAndFeel = defaultLookAndFeel;
            prefs.putBoolean("first_time", false);
            
        } else {
            // this following look and feels are included in my NetBeans RCP apps by default.
            switch (lookAndFeelClassStr) {
                case "javax.swing.plaf.metal.MetalLookAndFeel": // Metal
                    lookAndFeel = new MetalLookAndFeel();
                    break;
                case "javax.swing.plaf.nimbus.NimbusLookAndFeel":  // Nimbus
                    lookAndFeel = new NimbusLookAndFeel();
                    break;
                case "com.sun.java.swing.plaf.motif.MotifLookAndFeel": // CDE/Motif
                    lookAndFeel = new MotifLookAndFeel();
                    break;
                case "com.sun.java.swing.plaf.windows.WindowsLookAndFeel": // Windows
                    lookAndFeel = new WindowsLookAndFeel();
                    break;
                case "com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel": // Windows Classic
                    lookAndFeel = new WindowsClassicLookAndFeel();
                    break;
                case "org.netbeans.swing.laf.dark.DarkMetalLookAndFeel": // Dark Metal
                    lookAndFeel = new DarkMetalLookAndFeel();
                    break;
                default: // if it didn't match one of the defaults then check the list of extra look and feels.
                    for (LookAndFeel laf : extraLookAndFeels) {
                        if (laf.getClass().getTypeName().equals(lookAndFeelClassStr)) {
                            lookAndFeel = laf;
                            break;
                        }
                    }

                    // couldn't find a match so use the default provided to the constructor.
                    if (lookAndFeel == null) {
                        prefs.put("laf", defaultLookAndFeel.getClass().getTypeName());
                        lookAndFeel = defaultLookAndFeel;
                    }
                    break;
            }
        }
        setLookAndFeel(lookAndFeel);
    }

    /**
     * This will set the look and feel to the value provided.  If look and feel provided is null, then the default provided to the constructor will be used.
     */
    public void setLookAndFeel(LookAndFeel lookAndFeel) {
        LookAndFeel tmpLookAndFeel = lookAndFeel;

        if (tmpLookAndFeel == null) {
            tmpLookAndFeel = defaultLookAndFeel;
        }

        Preferences prefs = getPreferences();

        for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
            if ("Dark Nimbus".equals(info.getName())) {
                prefs.putBoolean("dark.themes.installed", true); //NOI18N
                break;
            }
        }

        try {
            // don't use the method that requires a class name because it tries to get the class loader from the system but the class loader is not know within this validate method yet.  Also, I don't use installLookAndFeel because that causes the L&F to show up twice in the L&F comboBox in the appearance panel and I get strange behavior sometimes.
            UIManager.setLookAndFeel(tmpLookAndFeel);
        } catch (UnsupportedLookAndFeelException ex) {
            Exceptions.printStackTrace(ex);
        }
    }

}




Hope this helps someone else.