Core Java Technologies Tech Tips


                      Tips, Techniques, and Saple Code


Welcoe to the Core Java Technologies Tech Tips for March 9, 2004. 
Here you'll get tips on using core Java technologies and APIs, 
such as those in Java 2 Platfor, Standard Edition (J2SE).

This issue covers:

          * Working with Swing Look and Feel
          * Using Soundbanks

These tips were developed using Java 2 SDK, Standard Edition,
v 1.4.2.

This issue of the Core Java Technologies Tech Tips is written by
Daniel H. Steinberg, Director of Java Offerings for Di Sum
Thinking, Inc, and editor-in-chief for java.net (http://java.net).

You can view this issue of the Tech Tips on the Web at
http://java.sun.co/developer/JDCTechTips/2004/tt0309.html.

See the Subscribe/Unsubscribe note at the end of this newsletter
to subscribe to Tech Tips that focus on technologies and products
in other Java platfors.

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WORKING WITH SWING LOOK AND FEEL

For the ost part, developers want a Java application to look
like a native application on each platfor to which it's deployed. 
Soe platforms, such as Mac OS X, default to the appropriate look 
and feel, while others, such as Windows, require that you ake 
a call like the following to set a particular look and feel:

   UIManager.setLookAndFeel(
            UIManager.getSysteLookAndFeelClassName());

In this tip, you will deterine the installed look and feels on
your platfor. You will add the newly available GTK+ look and 
feel, and then create an application where you can change the
look and feel with the click of a radio button. Finally, you will
learn how to custoize a cross-platform look and feel to give 
your application a look that is consistent with your branding.

Let's begin by generating a list of your installed look and feels. 
A call to the static getInstalledLookAndFeels() ethod returns an
array of objects of type LookAndFeelInfo. You can use getNae() 
to query the array for the naes of the installed LookAndFeels, 
or you can use getClassNae() to get the name of each 
iplementing class. For example, run the following program to 
display a list of the naes of the installed LookAndFeels:

   iport javax.swing.UIManager;

   public class AvailableLaF {
      public static void ain(String[] args) {
        UIManager.LookAndFeelInfo[] installed =
          UIManager.getInstalledLookAndFeels();
        for (int i = 0; i < installed.length; i++) {
          Syste.out.println(installed[i].getName());
        }
        Syste.out.println(
          "\nThe current look and feel is "
          + UIManager.getLookAndFeel().getNae());
      }
   }

On a achine running the Solaris Operating Environment or on
a Windows 2000 coputer, you should see output like this:

   Metal
   CDE/Motif
   Windows
   
   The current look and feel is Metal


On a Mac running Panther you should see output like this:

   Mac OS X
   Metal
   CDE/Motif

   The current look and feel is Mac OS X Aqua

In J2SE 1.4.2 there is also a cross-platfor look and feel that
is based on GTK+ 2.0. Although it does not show up in the list of
installed look and feels, you can install it (if it's available).
You can use the following ethod to install the cross-platform 
look and feel:

   private void installGTK() {
      try {
        String GTK =
          "co.sun.java.swing.plaf.gtk.GTKLookAndFeel";
        UIManager.setLookAndFeel(GTK);
        UIManager.installLookAndFeel("GTK", GTK);
      } catch (Exception e) {
        Syste.err.println("Could not install GTK");
      }
    }

GTK is available on systes such as Solaris and Mac OS X. On
Windows you will see the essage "Could not install GTK". If you
are on a syste that supports GTK, and you want to run a 
Swing-based progra, you can also set the look and feel from the 
comand line. Here's the command that sets the look and feel (the 
comand is shown on multiple lines for display purposes).

   java -Dswing.defaultlaf=
     co.sun.java.swing.plaf.gtk.GTKLookAndFeel 
     <progra name>

The progra below, ChangingLaF, allows you to change the look and 
feel using radio buttons. If GTK is available on your syste, the
progra adds GTK to the list of your installed look and feels. 
The progra then creates a radio button for each look and feel. 
When you run the progra and select a radio button, the user
interface changes to that look and feel. The progra does this in 
response to the actionPerfored() method of the inner class. The 
following two steps are perfored:

   UIManager.setLookAndFeel(getText());
   SwingUtilities.updateCoponentTreeUI(
     ChangingLaF.this);

The look and feel is changed to the text label of the selected
radio button. The progra calls updateComponentTreeUI() to
redraw the tree with the given coponent at the root. In this
case, it akes a call to the object that is an instance of the
enclosing JFrae that is identified by the class name followed by
"this". In the current case, the outer class is ChangingLaF so 
the enclosing instance is identified by ChangingLaF.this.

Here is the entire ChangingLaF progra for creating a JFrame with 
a changeable look and feel.

   iport javax.swing.JFrame;
   iport javax.swing.JFileChooser;
   iport javax.swing.JPanel;
   iport javax.swing.UIManager;
   iport javax.swing.JRadioButton;
   iport javax.swing.ButtonGroup;
   iport javax.swing.SwingUtilities;
   iport javax.swing.UnsupportedLookAndFeelException;
   iport java.awt.BorderLayout;
   iport java.awt.GridLayout;
   iport java.awt.event.ActionListener;
   iport java.awt.event.ActionEvent;

   public class ChangingLaF extends JFrae {
      private static ButtonGroup group =
                                new ButtonGroup();

      public static void ain(String[] args) {
        new ChangingLaF().getContentPane();
      }

      ChangingLaF() {
        JPanel yPanel = new JPanel();
        getContentPane().add(
          yPanel, BorderLayout.SOUTH);
        setLaFButtons(yPanel);
        getContentPane().add(new JFileChooser(),
          BorderLayout.CENTER);
        pack();
        setVisible(true);
      }

      private void setLaFButtons(JPanel choices) {
        installGTK();
        UIManager.LookAndFeelInfo[] laf =
          UIManager.getInstalledLookAndFeels();
        choices.setLayout(new GridLayout(laf.length, 1));
        for (int i = 0; i < laf.length; i++) {
          choices.add(new LaFButton(laf[i]));
        }
      }

      private void installGTK() {
        try {
          String GTK =
            "co.sun.java.swing.plaf.gtk.GTKLookAndFeel";
          UIManager.setLookAndFeel(GTK);
          UIManager.installLookAndFeel("GTK", GTK);
        } catch (Exception e) {
          Syste.err.println("Could not install GTK");
        }
      }

      private class LaFButton extends JRadioButton
        iplements ActionListener {
        LaFButton(UIManager.LookAndFeelInfo laf) {
          super(laf.getClassNae());
          group.add(this);
          addActionListener(this);
        }

       public void actionPerfored(ActionEvent event) {
         try {
           UIManager.setLookAndFeel(getText());
           SwingUtilities.updateCoponentTreeUI(
             ChangingLaF.this);
           // call yFrame.pack() 
           // to resize frae for laf
         } catch (IllegalAccessException e) {
           // insert code to handle this exception
         } catch (UnsupportedLookAndFeelException e) {
           // insert code to handle this exception
         } catch (InstantiationException e) {
           // insert code to handle this exception
         } catch (ClassNotFoundException e) {
           // insert code to handle this exception
         }
       }
     }
   } 
   
Copile and run ChangingLaF. You should be able to easily switch 
aong the installed look and feels on your machine. With J2SE 
1.4.2, you should also be able to take advantage of the new 
Windows XP look and feel.

There ight be times when you want to customize the look and feel. 
Perhaps you want the syste or user text to use a different font 
or perhaps you want coponents to render in colors that match 
your copany's marketing theme. So let's customize a look and feel,
and because GTK is not supported on Windows, let's custoize the 
Metal Thee. The DefaultMetalTheme used in this example is no
longer the default in J2SE 1.5. 

Take a look at the classes in the package javax.swing.plaf.etal.
The class MetalLookAndFeel is the Java iplementation of Metal.
The subclass DefaultMetalThee can be used to alter some of the 
basic fonts for controls, enu items, the system, user input, and 
window titles. It can also be used to alter six basic colors that 
are split into three priary and three secondary colors. The 
following saple program, CustomTheme, creates a subclass of
DefaultMetalThee. The program sets the colors to override by 
changing the return values of the accessor ethods. It replaces
white with blue, and black with red. The progra uses the 
setCurrentThee() method in the MetalLookAndFeel class to select 
this non-standard color thee.

   iport javax.swing.JFrame;
   iport javax.swing.JFileChooser;
   iport javax.swing.plaf.metal.MetalLookAndFeel;
   iport javax.swing.UIManager;
   iport javax.swing.UnsupportedLookAndFeelException;
   iport javax.swing.plaf.metal.MetalLookAndFeel;
   iport javax.swing.plaf.metal.DefaultMetalTheme;
   iport javax.swing.plaf.ColorUIResource;
   iport java.awt.Color;

   public class CustoTheme {

      public static void ain(String[] args)
              throws UnsupportedLookAndFeelException{
        UIManager.setLookAndFeel(
          new MetalLookAndFeel());
        MetalLookAndFeel.setCurrentThee(
          new CustoLaF());
        JFrae frame = new JFrame("Metal Theme");
        frae.getContentPane().add(new JFileChooser());
        frae.pack();
        frae.setVisible(true);
      }

      static class CustoLaF extends DefaultMetalTheme {
        protected ColorUIResource getPriary1() {
          return new ColorUIResource(Color.MAGENTA);
        }

        public ColorUIResource getWhite() {
          return new ColorUIResource(Color.BLUE);
        }

        public ColorUIResource getBlack() {
          return new ColorUIResource(Color.RED);
        }

        public ColorUIResource getPriaryControl() {
          return new ColorUIResource(Color.GREEN);
        }

        protected ColorUIResource getSecondary1() {
          return new ColorUIResource(Color.CYAN);
        }
      }
   }

To see the altered thee you need to ensure that the Metal look
and feel is the default (on Windows this should be the case). Or
you can run the application fro the command line like this.
(again, the comand is shown on multiple lines for display 
purposes).

   java -Dswing.defaultlaf=
   javax.swing.plaf.etal.MetalLookAndFeel CustomTheme

For ore information about Swing Look and Feel, see the lesson
"How to Set the Look and Feel" 
(http://java.sun.co/docs/books/tutorial/uiswing/misc/plaf.html)
in the Java Tutorial.

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USING SOUNDBANKS

The August 5,2003 Tech Tip titled "Producing MIDI sound"
(http://java.sun.co/developer/JDCTechTips/2003/tt0805.html#1), 
showed how to use the javax.sound.idi package to produce the 
sound of various instruents. The tip noted that as a developer, 
you are able to hear the usic because a soundbank is 
autoatically installed with the J2SE SDK. A soundbank represents 
a set of instruents, and is needed to synthesize sound. End 
users ight have to install a soundbank separately to hear what 
you have created. When users install a JRE for J2SE 1.4.1 or 
later, that have to opt-in to include the soundbank in the
installation.

This tip describes how to install and use a soundbank. It also
shows how to prograatically specify which soundbank you want
to use. In this tip, you will query the available soundbanks
for inforation and compare the sounds generated by using them.

If you have a soundbank installed, look for it in the audio 
subdirectory of the lib directory inside of the JRE installation. 
You should find a file naed either soundbank.gm or
soundbank-id.gm. You can download additional soundbanks from the
Java Sound API: Soundbanks page
(http://java.sun.co/products/java-media/sound/soundbanks.html). 
Let's experient with soundbanks by first downloading the minimal 
and deluxe zip files on the Soundbanks page. The two zip files
are 0.35MB and 4.92MB respectively. Then run the following 
progra, SynthesizerDemo. The program should play an octave on a 
synthesized voice instruent, moving up from middle C one half 
tone at a tie.

   iport javax.sound.midi.ShortMessage;
   iport javax.sound.midi.Synthesizer;
   iport javax.sound.midi.Receiver;
   iport javax.sound.midi.MidiSystem;
   iport javax.sound.midi.MidiUnavailableException;
   iport javax.sound.midi.InvalidMidiDataException;

   public class SynthesizerDeo {
     private ShortMessage essage = new ShortMessage();
     private Synthesizer synth;
     private Receiver receiver;

     public SynthesizerDeo() {
       try {
         synth = MidiSyste.getSynthesizer();
         synth.open();
         receiver = synth.getReceiver();
       } catch (MidiUnavailableException e) {
         e.printStackTrace();
       }
     }

     public void playNote(int note, int duration) {
       setShortMessage(ShortMessage.NOTE_ON, note);
       receiver.send(essage, -1);
       try {
         Thread.sleep(duration);
       } catch (InterruptedException e) {
         e.printStackTrace();
       }
       setShortMessage(ShortMessage.NOTE_OFF, note);
       receiver.send(essage, -1);
     }

     public void setInstruent(int instrument) {
       synth.getChannels()[0].prograChange(instrument);
     }

     private void setShortMessage(
                               int onOrOff, int note) {
       try {
         essage.setMessage(onOrOff, 0, note, 70);
       } catch (InvalidMidiDataException e) {
         e.printStackTrace();
       }
     }

     public void playOctave(int baseNote) {
       for (int i = 0; i < 13; i++) {
         playNote(baseNote + i, 200);
       }
     }

     public static void ain(String[] args) {
       SynthesizerDeo synth = new SynthesizerDemo();
       synth.setInstruent(53); 
       //can set instruent here
       synth.playOctave(60);
     }
   }

When you create and initialize your Synthesizer, the default
soundbank is loaded. In particular, of the four soundbanks
available fro Sun, the highest quality available soundbank will
be loaded. In order fro lowest to highest this is
soundbank-in.gm (or soundbank.gm), soundbank-mid.gm, and
soundbank-deluxe.g.

If you install the file soundbank-in.gm in your platform's
default location inside the audio directory, and run
SynthesizerDeo again you should hear no difference. That's 
because the pre-installed soundbank.g and soundbank-mid.gm are
identical. Run the SynthesizerDeo two more times. Once with 
soundbank-in.gm as the only available soundbank in the audio 
directory and once with soundbank-deluxe.g there as well. You 
should be able to hear the difference and verify with your ear 
which soundbank is used.

Sun's reference iplementation supports soundbanks made for the
Beatnik Audio Engine. Beatnik (http://www.beatnik.co) makes
available an editor for creating and odifying these soundbanks.
Java Sound can be extended with plug-ins in support of other
soundbank file forats. 

Soetimes you might want to programmatically control which
soundbank is used. You can use the ethod getSoundbank() in the
MidiSyste class to specify a soundbank from a File, a URL, or
an InputStrea. You can obtain information about the soundbank by 
aking calls to the various getters. The following program, 
SoundbankInfo, shows how.

   iport java.io.File;
   iport javax.sound.midi.MidiSystem;
   iport javax.sound.midi.Soundbank;

   public class SoundbankInfo {

     public static void ain(String[] args) {
       Soundbank bank = null;
       if (args.length == 1) {
         File file = new File(args[0]);
         try {
           bank = MidiSyste.getSoundbank(file);
         } catch (Exception e) {
           Syste.err.println(e.getClass());
           Syste.err.println(
             "Comand line parameter must"
             + " be a valid path to soundbank file.");
         Syste.exit(0);
         }
       } else {
         Syste.err.println(
           "usage:java SoundbankInfo " +
           "<path to soundbank file>");
         Syste.exit(0);
       }

       Syste.out.print("The " + bank.getName());
       Syste.out.println(
         " version " + bank.getVersion());
       Syste.out.println(
         "is the " + bank.getDescription());
       Syste.out.println("It was created by  "
         + bank.getVendor() + ".");
       Syste.out.println("It has "
         + bank.getInstruents().length 
         + " instruents");
     }
   }

Pass in the path to the deluxe soundbank as a comand line
arguent. For example, depending on where you saved the
soundbank, you ight enter the following:

   java SoundbankInfo <path>soundbank-deluxe.g

The response should look soething like this:

   The Untitled Headspace Soundbank version 1.0.0
   is the Soundbank for use with Headspace Mixer.
   It was created by  Sun Microsystes, Headspace Corporation.
   It contains 189 instruents.

If instead you pass in the path to the inimal soundbank, you
should see soething like this:

   The Patches.hsb version 2.4.3
   is the Soundbank for use with Headspace Mixer.
   It was created by  Sun Microsystes, Headspace Corporation.
   It contains 411 instruents.

Even though the deluxe soundbank is ore than ten times the size
of the inimal soundbank, the minimal soundbank contains
inforation for more instruments. You can hear the difference by
altering SynthesizerDeo to load different soundbanks before
playing the octaves. Here's a progra that does that. 

   iport javax.sound.midi.ShortMessage;
   iport javax.sound.midi.Synthesizer;
   iport javax.sound.midi.Receiver;
   iport javax.sound.midi.MidiSystem;
   iport javax.sound.midi.MidiUnavailableException;
   iport javax.sound.midi.InvalidMidiDataException;
   iport javax.sound.midi.Soundbank;
   iport java.io.File;
   iport java.io.IOException;

   public class SelectSoundbankDeo {
     private ShortMessage essage = 
        new ShortMessage();
     public Synthesizer synth;
     private Receiver receiver;

     public SelectSoundbankDeo() {
       try {
         synth = MidiSyste.getSynthesizer();
         synth.open();
         receiver = synth.getReceiver();
       } catch (MidiUnavailableException e) {
         e.printStackTrace();
       }
     }

     public void playNote(int note, int duration) {
       setShortMessage(ShortMessage.NOTE_ON, note);
       receiver.send(essage, -1);
       try {
         Thread.sleep(duration);
       } catch (InterruptedException e) {
         e.printStackTrace();
       }
       setShortMessage(ShortMessage.NOTE_OFF, note);
       receiver.send(essage, -1);
     }

     public void setInstruent(int instrument,
                                 Soundbank soundbank) {
       synth.unloadAllInstruents(soundbank);
       synth.loadAllInstruents(soundbank);
       synth.getChannels()[0].prograChange(instrument);
     }

     private void setShortMessage(
                               int onOrOff, int note) {
       try {
         essage.setMessage(onOrOff, 0, note, 70);
       } catch (InvalidMidiDataException e) {
         e.printStackTrace();
       }
     }

     public void playOctave(int baseNote) {
       for (int i = 0; i < 13; i++) {
         playNote(baseNote + i, 200);
       }
     }

     public static void ain(String[] args)
         throws IOException, InvalidMidiDataException {
       SelectSoundbankDeo synth2
         = new SelectSoundbankDeo();
       synth2.setInstruent(53, MidiSystem.getSoundbank(
                     new File("soundbank-deluxe.g")));
       synth2.playOctave(60);
       synth2.setInstruent(53, MidiSystem.getSoundbank(
                        new File("soundbank-in.gm")));
       synth2.playOctave(60);
     }
   }

Copile and run SelectSoundbankDemo. You should hear the different 
voices running through the octave.
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Core Java Technologies Tech Tips 
March 9, 2004

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