Centralização de texto

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
 
public class TextPaneAttributes extends JFrame
{
	public TextPaneAttributes()
	{
		JTextPane textPane = new JTextPane();
		StyledDocument doc = textPane.getStyledDocument();
 
		//  Set alignment to be centered for all paragraphs
 
		MutableAttributeSet standard = new SimpleAttributeSet();
		StyleConstants.setAlignment(standard, StyleConstants.ALIGN_CENTER);
		doc.setParagraphAttributes(0, 0, standard, true);
 
		//  Define a keyword attribute
 
		MutableAttributeSet keyWord = new SimpleAttributeSet();
		StyleConstants.setForeground(keyWord, Color.red);
		StyleConstants.setItalic(keyWord, true);
 
		//  Add initial text
 
		textPane.setText( "one\ntwo\nthree\nfour\nfive\nsix\nseven\neight\n" );
 
		//  Highlight some keywords
 
		doc.setCharacterAttributes(0, 3, keyWord, false);
		doc.setCharacterAttributes(19, 4, keyWord, false);
 
		//  Add some text
 
		try
		{
			doc.insertString(0, "Start of text\n", null );
			doc.insertString(doc.getLength(), "End of text\n", keyWord );
		}
		catch(Exception e) {}
 
		//  Add text pane to frame
 
		JScrollPane scrollPane = new JScrollPane( textPane );
		scrollPane.setPreferredSize( new Dimension( 200, 200 ) );
		getContentPane().add( scrollPane );
 
		//  Add a bold button
		JButton button = new JButton("bold");
		getContentPane().add(button, BorderLayout.SOUTH);
		button.addActionListener( new ActionListener()
		{
			public void actionPerformed(ActionEvent e)
			{
				new StyledEditorKit.BoldAction().actionPerformed(null);
			}
		});
 
	}
 
	public static void main(String[] args)
	{
		TextPaneAttributes frame = new TextPaneAttributes();
		frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
		frame.pack();
		frame.setVisible(true);
	}
}