JDK-4098739 : JDK 1.1.5 Scrollbar maximum value behavior differs from API
  • Type: Bug
  • Component: docs
  • Sub-Component: guides
  • Affected Version: 1.1.5
  • Priority: P3
  • Status: Closed
  • Resolution: Duplicate
  • OS: solaris_2.5.1
  • CPU: sparc
  • Submitted: 1997-12-11
  • Updated: 1998-01-05
  • Resolved: 1998-01-05
Related Reports
Duplicate :  

Name: joT67522			Date: 12/11/97

There seems to be a long-standing bug in the
Solaris implementation of the JDK 1.1.x Scrollbar
class.  According to the API documentation, if
you create a scrollbar with the specification:
   minimum = 0
   visible = 64
   maximum = 255
then the resulting scrollbar should have a track
of length 255+64, a slider of length 64, and a
maximum value of 255.  This is precisely the
example given in the API documentation.  I have
written a small applet to test this (see the
Scrolltest class below.)  On all of the browsers
and platforms I have tested (Solaris, Win95,
WinNT, and Mac, with Netscape and MSIE), this is
the behavior I see.

However, on Solaris, when I run the same applet
with the JDK 1.1.5 appletviewer I get a scrollbar
whose maximum value is 191 (255-64.)  This
disagrees with the behavior specified in the API

Below is both the source code for the small
applet, and a sample HTML file that can be used
to load it.

Here is the HTML file:

<head><title>Scrollbar Test</title>
<body bgcolor=#ffffff>
<h1>Scrollbar Test</h1>
<applet code="Scrolltest" width=350	height=350 align=top>
Could not display applet.

Here is the code:

// Scrolltest

// This class just puts up a simple scrollbar.  It was written to test
// the differences in the interpretation of the "maximum" parameter
// between different JDK's & browsers.

import java.awt.*;
import java.applet.*;

public class Scrolltest extends Applet {
	private static int MINIMUM = 0;
	private static int VISIBLE = 64;
	private static int MAXIMUM = 255;

	private Scrollbar sbar = new Scrollbar(Scrollbar.VERTICAL, 0,
																				 VISIBLE, MINIMUM, MAXIMUM);
	private TextField sval = new TextField(50);

	public void init() {
		setLayout(new BorderLayout());
		Panel specPanel = new Panel();
		specPanel.setLayout(new FlowLayout());
		specPanel.add(new Label("Minimum: " + MINIMUM));
		specPanel.add(new Label("Visible: " + VISIBLE));
		specPanel.add(new Label("Maximum: " + MAXIMUM));
		add("Center", specPanel);
		add("East", sbar);
		sval.setText("Current value = " + sbar.getValue());
		add("South", sval);

	public boolean handleEvent(Event e) {
		if (e.target == sbar) {
			sval.setText("Current value = " + sbar.getValue());
		return super.handleEvent(e);

(Review ID: 21798)

WORK AROUND Name: joT67522 Date: 12/11/97 Make your own scrollbar class. I suggest subclassing Panel, and putting an awt Scrollbar in the Panel. You can detect the prescence of the bug by attempting to set the value of the scrollbar to the maximum. If this fails, then the bug exists and you can adjust the maximum value to take it into account. ======================================================================