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/*************************************************************************
*
* $RCSfile: MessageArea.java,v $
*
* $Revision: 1.3 $
*
* last change: $Author: hr $ $Date: 2003/06/30 15:06:53 $
*
* The Contents of this file are made available subject to the terms of
* the BSD license.
*
* Copyright (c) 2003 by Sun Microsystems, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Sun Microsystems, Inc. nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*************************************************************************/
import java.awt.Font;
import java.awt.Rectangle;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JScrollBar;
/** A message area displays text in a scrollable text widget. It is a
singleton. Other objects can access it directly to display messages.
*/
public class MessageArea
extends JScrollPane
{
public static synchronized MessageArea Instance ()
{
if (saInstance == null)
saInstance = new MessageArea ();
return saInstance;
}
/** Create a new message area. This method is private because the class is
a singleton and may therefore not be instanciated from the outside.
*/
private MessageArea ()
{
maText = new JTextArea();
maText.setBackground (new Color (255,250,240));
maText.setFont (new Font ("Helvetica", Font.PLAIN, 9));
setViewportView (maText);
setVerticalScrollBarPolicy (JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
setHorizontalScrollBarPolicy (JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
printMessage (
"class path is " + System.getProperty ("java.class.path") + "\n");
}
/** Show the given string at the end of the message area and scroll to make
it visible.
*/
public static synchronized void print (String aMessage)
{
Instance().printMessage(aMessage);
}
/** Show the given string at the end of the message area and scroll to make
it visible.
*/
public static void println (String aMessage)
{
Instance().printMessage (aMessage+"\n");
}
public void paintComponent (Graphics g)
{
// Synchronize with the graphics object to prevent paint problems.
// Remember that this is not done by Swing itself.
synchronized (g)
{
JScrollBar sb = getVerticalScrollBar();
if (sb != null)
{
int nScrollBarValue = sb.getMaximum() - sb.getVisibleAmount() - 1;
sb.setValue (nScrollBarValue);
}
super.paintComponent (g);
}
}
/** Append the given string to the end of the text and scroll so that it
becomes visible. This is an internal method. Use one of the static
and public ones.
*/
private synchronized void printMessage (String aMessage)
{
maText.append (aMessage);
}
private static MessageArea saInstance = null;
private JTextArea maText;
}
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