JTextPane textPane = new JTextPane();

// Makes text red
Style style = textPane.addStyle("Red", null);
StyleConstants.setForeground(style, Color.red);

// Inherits from "Red"; makes text red and underlined
style = textPane.addStyle("Red Underline", style);
StyleConstants.setUnderline(style, true);

// Makes text 24pts
style = textPane.addStyle("24pts", null);
StyleConstants.setFontSize(style, 24);

// Makes text 12pts
style = textPane.addStyle("12pts", null);
StyleConstants.setFontSize(style, 12);

// Makes text italicized
style = textPane.addStyle("Italics", null);
StyleConstants.setItalic(style, true);

// Makes text bold
style = textPane.addStyle("Bold", null);
StyleConstants.setBold(style, true);

JTextPane c = textPane;
// Construct a sorted list of style names
DefaultStyledDocument doc = (DefaultStyledDocument)textPane.getDocument();
java.util.List l = new ArrayList();
Enumeration enum = doc.getStyleNames();
while (enum.hasMoreElements()) {
    l.add(enum.nextElement());
}
Collections.sort(l);

// First sub menu applies character attributes
final JPopupMenu menu = new JPopupMenu();
JMenu submenu = new JMenu("Character");
for (int i=0; i<l.size(); i++) {
    submenu.add(new JMenuItem(new DoStyleAction((String)l.get(i), CHARACTER)));
}
menu.add(submenu);

// Second sub menu applies paragraph attributes
submenu = new JMenu("Paragraph");
for (int i=0; i<l.size(); i++) {
    submenu.add(new JMenuItem(new DoStyleAction((String)l.get(i), PARAGRAPH)));
}
menu.add(submenu);

// Third submenu applies logical attributes
submenu = new JMenu("Logical");
for (int i=0; i<l.size(); i++) {
    submenu.add(new JMenuItem(new DoStyleAction((String)l.get(i), LOGICAL)));
}
menu.add(submenu);

// Add a listener to display pop-up
textPane.addMouseListener(new MouseAdapter() {
    public void mousePressed(MouseEvent evt) {
        if (evt.isPopupTrigger()) {
            menu.show(evt.getComponent(), evt.getX(), evt.getY());
        }
    }
    public void mouseReleased(MouseEvent evt) {
        if (evt.isPopupTrigger()) {
            menu.show(evt.getComponent(), evt.getX(), evt.getY());
        }
    }
});

static final int CHARACTER = 1;
static final int PARAGRAPH = 2;
static final int LOGICAL = 3;

// Assumes the style name is the same as the action name.
// The type specifies how the style should be applied.
// The style is applied to the text within the selection.
public static class DoStyleAction extends StyledEditorKit.StyledTextAction {
    int type;
    public DoStyleAction(String styleName, int type) {
        super(styleName);
        this.type = type;
    }
    public void actionPerformed(ActionEvent e) {
        JTextPane c = (JTextPane)getEditor(e);
        if (c != null) {
            String styleName = e.getActionCommand();
            StyledDocument doc = (StyledDocument)c.getDocument();

            switch (type) {
            case CHARACTER:
                c.setCharacterAttributes(doc.getStyle(styleName), true);
                break;
            case PARAGRAPH:
                c.setParagraphAttributes(doc.getStyle(styleName), true);
                break;
            case LOGICAL:
                c.setLogicalStyle(doc.getStyle(styleName));
                break;
            }
        }
    }
}