Help is available for each task, or you can go straight to the solution source code.

Task 1

Import the Swing text package. The text-handling support classes are all located here.

import javax.swing.text.*;

Create an instance variable pane of type JTextPane, and an instance variable doc of type StyledDocument. The document represents the model of the text, while the pane represents the view of it to the user.

JTextPane pane;
StyledDocument doc;

Create a JTextPane, place in JScrollPane, and place in center of the screen. You will need to create a DefaultStyledDocument, and then pass that along to the JTextPane constructor.

Remember to save the references to the JTextPane and StyledDocument in the instance variables, as they will be needed later.

doc = new DefaultStyledDocument();
pane = new JTextPane (doc);
JScrollPane sp = new JScrollPane (pane);
c.add(sp, BorderLayout.CENTER);

The "Load Text" menu item under the File menu calls the doLoadCommand() method to load a text file. The method has two pieces missing:

• Clear out the current document
• For each line read in from the file, add the line to the document with the default style

To clear out the current document, create a new document:

pane.setStyledDocument (
     doc = new DefaultStyledDocument());

To insert into the document, use the new StyledDocument just created:

doc.insertString(doc.getLength(), 
  new String (buffer, 0, len), null);

For the Color menu, add a ColoredBox icon for each menu item.

The ColoredBox class is provided as a support class. Its constructor requires a Color.

At the appropriate location in the source, add the following lines:

  item.setIcon (new ColoredBox(Color.red));
  ...
  item.setIcon (new ColoredBox(Color.orange));
  ...
  item.setIcon (new ColoredBox(Color.yellow));
  ...
  item.setIcon (new ColoredBox(Color.green));
  ...
  item.setIcon (new ColoredBox(Color.blue));
  ...
  item.setIcon (new ColoredBox(Color.magenta));

For each of the color menu items, add an ActionListener to change the foreground color of the text.

The StyledEditorKit class has a static inner class to help here. Its called ForegroundAction and takes two parameters. The first is a text string describing the change, while the second is the new foreground color.

At the appropriate location in the source, add the following lines:

item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-red", Color.red));
...
item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-orange", Color.orange));
...
item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-yellow", Color.yellow));
...
item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-green", Color.green));
...
item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-blue", Color.blue));
...
item.addActionListener (new
  StyledEditorKit.ForegroundAction (
    "set-foreground-magenta", Color.magenta));

For the Custom Color menu item, you need to complete the doColorCommand() method to allow the user to enter any color, besides just the canned colors. In doColorCommand(), show a JColorChooser, and change the foreground color to the color selected.

Pick a default color to use as the last parameter to showDialog.

Color color = JColorChooser.showDialog(
  this, "Color Chooser", Color.cyan);

If the returned value is not null, change the foreground text color:

if (color != null) {
  MutableAttributeSet attr = 
      new SimpleAttributeSet();
  StyleConstants.setForeground(attr, color);
  pane.setCharacterAttributes(attr, false); 
}

Most of the Font change support menu is already done for you. The only two menu items that need action listeners are the Bold and Italic entries. Add an ActionListener to each of these items to change the appropriate font characteristic.

Like the ForegroundAction inner class, there are two more inner classes for these events. They are called BoldAction and ItalicAction.

Be sure to check how the font size and family change, too.

For font bold and italics, add the following lines at the appropriate location in the source:

item.addActionListener (
  new StyledEditorKit.BoldAction ());
...
item.addActionListener (
  new StyledEditorKit.ItalicAction ());

For the Image File menu item, you need to complete the doInsertImageCommand() method so that a user can display an image within the JTextPane. The main JFileChooser usage source has already been created for you, you only need to finish the approve response, which is called when the user selects the Okay or Open button. Here you need to find the image file selected, create an ImageIcon for it, and insert it into the JTextPane.

Use getSelectedFile() to find the selected File.

File file = chooser.getSelectedFile();

Get the file as an ImageIcon.

Icon icon = new ImageIcon (
                file.getAbsolutePath());

Use insertIcon() to add the icon to the pane.

pane.insertIcon (icon);

Save everything and compile the program. Then run it to see the results. Load a file and change its display style. You can save the document and reload the document as a serializable object. Also, try to add an image to the document.

javac Formatter.java
java Formatter

Return to Magercise 3

Copyright © 1998-1999 MageLang Institute. All Rights Reserved.