jan04_johnz.txt

TechTips.zip

that component is used in the dialog. This allows you to place 
icons in the buttons, for instance. More typically, you would 
provide an array of strings, and their labels would be used as the 
button labels. The initialValue is then used to select which of
the options gets the default selection.

The showOptionDialog method returns an int. This indicates the 
position selected from the options array. CLOSED_OPTION is still
returned if the user closed the dialog.

   String options[] = {"Yes", "Not Now", "Go Away"};
   int value = JOptionPane.showOptionDialog(
       component,
       "Lunch?",
       "Lunch Time",
       JOptionPane.YES_NO_OPTION, // Need something  
         JOptionPane.QUESTION_MESSAGE,
       null, // Use default icon for message type
       options,
       options[1]);
   if (value == JOptionPane.CLOSED_OPTION) {
     System.out.println("Closed window");
   } else {
     System.out.println("Selected: " + options[value]);
   }

If you don't want buttons, pass in an empty array for the options.

Adding Word Wrap

The JOptionPane component has a read-only property 
(MaxCharactersPerLineCount) for the maximum number of characters 
per line. By default, this is Integer.MAX_VALUE. By subclassing 
JOptionPane, you can override this setting. Changing this setting 
allows the component to word-wrap when a message is really long. 

   public static JOptionPane getNarrowOptionPane(
                       int maxCharactersPerLineCount) {
     // Our inner class definition
     class NarrowOptionPane extends JOptionPane {
       int maxCharactersPerLineCount;
       NarrowOptionPane(int maxCharactersPerLineCount) {
         this.maxCharactersPerLineCount = 
           maxCharactersPerLineCount;
       }
       public int getMaxCharactersPerLineCount() {
         return maxCharactersPerLineCount;
       }
     }


     return new NarrowOptionPane(
       maxCharactersPerLineCount);
   }


By subclassing, you can no longer use the static helper methods 
such as showMessageDialog. Here's how you manually create and 
show the component:

   String msg = "This is a really long message. ...";
   JOptionPane pane = getNarrowOptionPane(50);
   pane.setMessage(msg);
   pane.setMessageType(JOptionPane.INFORMATION_MESSAGE);
   JDialog dialog = pane.createDialog(
     component, "Width 50");
   dialog.show();

Of course, you can add a "\n" to the message, but then you have 
to count the characters per line.

Message as Object

At this point you might ask why the message argument to all the 
showXXXDialog methods is an Object. The answer is that it's 
because the message argument to all these methods doesn't have to 
be a String. You can pass in any Object. Each object is "added" 
to the message area, one on top of the other. For instance, if 
you pass in an array of two strings, it creates a message on two 
lines:

   String msg[] = {"Welcome", "Home"};
   JOptionPane.showMessageDialog(component, msg);

The objects you add can be components, icons, or objects. 
Components are added as such. Icons are shown in a label, as are 
strings. For other objects, their string representation 
(toString()) is shown. For instance, the following component can 
be added to an option pane. As the user changes the selection in 
the slider, the option pane's value is updated:

   public static JSlider getSlider(
                        final JOptionPane optionPane) {
     JSlider slider = new JSlider();
     slider.setMajorTickSpacing (10);
     slider.setPaintTicks(true);
     slider.setPaintLabels(true);
     ChangeListener changeListener = 
       new ChangeListener() {
       public void stateChanged(
                   ChangeEvent changeEvent) {
         JSlider theSlider = 
             (JSlider)changeEvent.getSource();
         if (!theSlider.getValueIsAdjusting()) {
           optionPane.setInputValue(
             new Integer(theSlider.getValue()));
         }
       }
     };
     slider.addChangeListener(changeListener);
     return slider;
   }

Because you have to pass the option pane to the method, here 
again, you can't use one of the shortcuts to create the dialog:

   JOptionPane optionPane = new JOptionPane();
   JSlider slider = getSlider(optionPane);
   Object msg[] = {"Select a value:", slider};
   optionPane.setMessage(msg);
   optionPane.setMessageType(
     JOptionPane.QUESTION_MESSAGE);
   optionPane.setOptionType(
     JOptionPane.OK_CANCEL_OPTION);
   JDialog dialog = optionPane.createDialog(
       Options.this, "Select Value");
   dialog.show();
   Object value = optionPane.getValue();
   if (value == null || !(value instanceof Integer)) {
     System.out.println("Closed");
   } else {
     int i = ((Integer)value).intValue();
     if (i == JOptionPane.CLOSED_OPTION) {
       System.out.println("Closed");
     } else if (i == JOptionPane.OK_OPTION) {
       System.out.println("OKAY - value is: " +
                  optionPane.getInputValue());
     } else if (i == JOptionPane.CANCEL_OPTION) {
       System.out.println("Cancelled");
     }
   }

Notice that as you start getting fancier with JOptionPane, you 
lose the ability to use the shortcut methods. And, you have to 
do special handling of the return value. You first need to use 
getValue for the JOptionPane to determine which button the user 
selected. Then, for when the user presses the OK button, you need
to use the getInputValue method to get the value from the 
underlying slider.

Sounds

Swing provides for auditory cues related to the four types of 
icons:

o OptionPane.errorSound 
o OptionPane.informationSound 
o OptionPane.questionSound 
o OptionPane.warningSound 

By setting these properties, you can get sounds when your option
panes are displayed. You can set the individual sounds with lines 
like the following:

   UIManager.put("OptionPane.questionSound", 
     "sounds/OptionPaneError.wav");

Or set all of them with the system defaults as follows:

   UIManager.put("AuditoryCues.playList",
     UIManager.get("AuditoryCues.defaultCueList"));

Audio cues are disabled by default because they might have 
problems on some platforms. It is recommended that you use them 
with care until the issues have been resolved.

Complete Example

Here is the source code for a complete example that uses the 
features explored in this tip.

   import javax.swing.*;
   import javax.swing.event.*;
   import java.awt.*;
   import java.awt.event.*;
   import java.util.Locale;

   public class Options extends JFrame {
     private static class FrameShower
         implements Runnable {
       final Frame frame;
       public FrameShower(Frame frame) {
         this.frame = frame;
       }
       public void run() {
         frame.show();
       }
     }

     public static JOptionPane getNarrowOptionPane(
         int maxCharactersPerLineCount) {
       // Our inner class definition
       class NarrowOptionPane extends JOptionPane {
         int maxCharactersPerLineCount;
         NarrowOptionPane(
                   int maxCharactersPerLineCount) {
           this.maxCharactersPerLineCount = 
              maxCharactersPerLineCount;
     }
         public int getMaxCharactersPerLineCount() {
           return maxCharactersPerLineCount;
         }
       }

    return new NarrowOptionPane(
               maxCharactersPerLineCount);
  }

     public static JSlider getSlider(
                        final JOptionPane optionPane) {
       JSlider slider = new JSlider();
       slider.setMajorTickSpacing (10);
       slider.setPaintTicks(true);
       slider.setPaintLabels(true);
       ChangeListener changeListener = 
                            new ChangeListener() {
         public void stateChanged(
                           ChangeEvent changeEvent) {
           JSlider theSlider = (
             JSlider)changeEvent.getSource();
           if (!theSlider.getValueIsAdjusting()) {
             optionPane.setInputValue(new Integer(  
               theSlider.getValue()));
           }
         }
       };
       slider.addChangeListener(changeListener);
       return slider;
     }

     public Options() {
       super("JOptionPane Usage");
       setDefaultCloseOperation(EXIT_ON_CLOSE);
       Container contentPane = getContentPane();
       contentPane.setLayout(new FlowLayout());
       JButton message = new JButton("Message");
       ActionListener messageListener = 
                               new ActionListener() {
         public void actionPerformed(ActionEvent e) {
           JOptionPane.showMessageDialog(
             Options.this, "Hello, World");
         }
       };
       message.addActionListener(messageListener);
       contentPane.add(message);
       JButton confirm = new JButton("Confirm");  
       ActionListener confirmListener = 
        new ActionListener() {
         public void actionPerformed(ActionEvent e) {
           int returnValue = 
             JOptionPane.showConfirmDialog(
           Options.this, "Lunch?");
           String message = null;           
           if (returnValue == JOptionPane.YES_OPTION) {
             message = "Yes";
           } else if (
               returnValue == JOptionPane.NO_OPTION) {
             message = "No";
           } else if (
               returnValue == JOptionPane.CANCEL_OPTION) {
             message = "Cancel";
           } else if (
               returnValue == JOptionPane.CLOSED_OPTION) {
             message = "Closed";
           }
           System.out.println("User selected: " + message);
         }
       };
       confirm.addActionListener(confirmListener);
       contentPane.add(confirm);
       JButton inputText = new JButton("Input Text");
       ActionListener inputTextListener = 
                               new ActionListener() {
         public void actionPerformed(ActionEvent e) {
           String value = 
             JOptionPane.showInputDialog("Name");
           System.out.println("Name: " + value);
         }
       };
       inputText.addActionListener(inputTextListener);
       contentPane.add(inputText);
       JButton inputCombo = new JButton("Input Combo");
       ActionListener inputComboListener = 
                                 new ActionListener() {
         public void actionPerformed(ActionEvent e) {
           String smallList[] = {
             "Sunday",
             "Monday",
             "Tuesday",
             "Wednesday",
             "Thursday",
             "Friday",
             "Saturday"
           };
           String value = 
             (String)JOptionPane.showInputDialog(
             Options.this, "Which Day?", "Day", 
             JOptionPane.QUESTION_MESSAGE, null, 
             smallList, smallList[smallList.length-1]);