Programatically displaying scrollbars of a JScrollPane

6 Message(s) by 4 Author(s) originally posted in java gui

From: Chanchal

Date: Thursday, September 27, 2007

Hi All,

I have a JScrollPane on a JFrame. The JScrollPane contain a JPanel.On
click

<hardware> To press and release a {button} on a {mouse} or
	other {pointing device}.  This generates an {event}, also
	specifying the screen position, which is processed by the
	{window manager} or {application program}.  On a mouse with
	more than one button, the unqualified term usually implies
	pressing the left-most button (with the right index finger),
	other buttons would be qualified, e.g. "{right-click}".
	{Keyboard} modifiers may also be used, e.g. "shift-click",
	meaning to hold down the shift key on the keyboard while
	clicking the mouse button.

	If the mouse moves while the button is pressed then this is a
	{drag}.

	(1995-03-14)

of a JButton, i'm adding new JButtons to this JPanel, side by
side.

import JAVAx.swing.*;
import JAVA.awt.event.*;

public class

1. <programming> The prototype for an {object} in an
	{object-oriented language}; analogous to a {derived type} in a
	{procedural language}.  A class may also be considered to be a
	set of objects which share a common structure and behaviour.
	The structure of a class is determined by the {class
	variables} which represent the {state} of an object of that
	class and the behaviour is given by a set of {methods}
	associated with the class.

	Classes are related in a {class hierarchy}.  One class may be
	a specialisation (a "{subclass}") of another (one of its
	"{superclasses}") or it may be composed of other classes or it
	may use other classes in a {client-server} relationship.  A
	class may be an {abstract class} or a {concrete class}.

	See also {signature}.

	2. <programming> See {type class}.

	3. <networking> One of three types of {Internet addresses}
	distinguished by their most significant bits.

	3. <language> A language developed by the {Andrew Project}.
	It was one of the first attempts to add {object-oriented}
	features to {C}.

	(1995-05-01)

DynamicScroll extends JFrame implements ActionListener{

private int

1. <programming> A common name for the {integer} data type.
	In {C} for example, it means a (signed) integer of the
	computer's native {word length}.

	2. <networking> The {top-level domain} for international
	organisations.

	(1999-01-26)

button

1. <electronics> {push-button}.

	2. <operating system> A graphical representation of an
	electrical {push-button} appearing as part of a {graphical
	user interface}.  Moving the {mouse pointer} over the
	graphical button and pressing one of the physical mouse
	buttons starts some software action such as closing a window
	or deleting a file.

	See also {radio button}.

	(1997-07-07)

Count = 0;
private JButton jButton1;
private JPanel jPanelInScrollPane;
private JScrollPane jScrollPane1;

public DynamicScroll() {
jScrollPane1 = new JScrollPane();
jPanelInScrollPane = new JPanel();
jButton1 = new JButton();

getContentPane().setLayout(null

<programming> A special value used in several languages to
	represent the thing referred to by an uninitialised pointer.

	<database> A special value that may be stored in some database
	columns to represent an unknown, missing, not applicable, or
	undefined value.  Nulls are treated completely differently
	from ordinary values when evaluating SQL expressions and there
	are several SQL constructs for dealing with nulls.

	(2003-06-17)

);
jPanelInScrollPane.setLayout(null);

jScrollPane1.setViewportView(jPanelInScrollPane);
getContentPane().add(jScrollPane1);
jScrollPane1.setBounds(40, 40, 320, 80);

jButton1.setText("Add Button");
jButton1.addActionListener(this);

getContentPane().add(jButton1);
jButton1.setBounds(150, 170, 120, 23);

}

public void actionPerformed(ActionEvent evt) {
JButton newButton = new JButton("Button "+ buttonCount);
newButton.setBounds( buttonCount * (100)+10, 5, 100, 50);
jPanelInScrollPane.add(newButton);
buttonCount ++ ;
jPanelInScrollPane.repaint();
jPanelInScrollPane.validate();
}

public static void main(String args[]) {
DynamicScroll ds = new DynamicScroll();
ds.setSize(400,300);
ds.setVisible(true);
}
}Starting from the 4th button which is added dynamically, the buttons
goes outside the JScrollPane. I want the scrollbars of the JScrollPane
to appear when the dynamically added buttons are outside the area of
the JScrollPane so that I can scroll and view all the added JButtons.
Kindly advice on how this can be done.

Thanks in advance

Chanchal

From: Andrew Thompson

Date: Thursday, September 27, 2007

wrote in message:
.

I have a JScrollPane on a JFrame. The JScrollPane contain a JPanel.On
click of a JButton, i'm adding new JButtons to this JPanel, side by
side.

Starting from the 4th button which is added dynamically, the buttons
goes outside the JScrollPane. I want the scrollbars of the JScrollPane
to appear when the dynamically added buttons are outside the area of
the JScrollPane so that I can scroll and view all the added JButtons.
Kindly advice on how this can be done.

Layouts, layouts, *layouts*!

This example doesn't quite have the shape or size
you originally had, but it ostensibly works.

<sscce>
import JAVA.awt.*;
import JAVA.awt.event.*;
import JAVAx.swing.*;
import JAVAx.swing.border.*;

public class DynamicScroll extends JFrame implements ActionListener{

private int buttonCount = 0;
private JButton jButton1;
private JPanel jPanelInScrollPane;
private JScrollPane jScrollPane1;

public DynamicScroll() {
setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
JPanel mainPanel = new JPanel( new BorderLayout(50,50) );
mainPanel.setBorder( new EmptyBorder(50,50,50,50) );

jPanelInScrollPane = new JPanel();
jScrollPane1 = new JScrollPane(jPanelInScrollPane);
jButton1 = new JButton("Add Button");

// have you not learned layouts yet?!
// 'null' layouts are the path

1. <networking> A {bang path} or explicitly routed {Internet
	address}; a node-by-node specification of a link between two
	machines.

	2. <file system> {pathname}.

	3. <operating system>  The list of directories the kernel
	(under {Unix}) or the command interpreter (under {MS-DOS})
	searches for {executables}.  It is stored as part of the
	{environment} in both operating systems.

	Other, similar constructs abound under Unix; the {C}
	{preprocessor}, for example, uses such a search path to locate
	"#include" files.

	[{Jargon File}]

	(1996-11-21)

to madness!
// the only time you should be setting a
// layout to null is for custom painting,
// and designing a new layout manager..
// considers - no, even then it is probably redundant
//getContentPane().setLayout(null);
jPanelInScrollPane.setLayout(new FlowLayout());

//jScrollPane1.setViewportView(jPanelInScrollPane);
mainPanel.add(jScrollPane1, BorderLayout.CENTER);
//jScrollPane1.setBounds(40, 40, 320, 80);

//jButton1.setText("Add Button");
jButton1.addActionListener(this);

mainPanel.add(jButton1, BorderLayout.SOUTH);
//jButton1.setBounds(150, 170, 120, 23);

setContentPane( mainPanel );
pack();

}

public void actionPerformed(ActionEvent evt) {
JButton newButton = new JButton("Button "+ buttonCount);
//newButton.setBounds( buttonCount * (100)+10, 5, 100, 50);
jPanelInScrollPane.add(newButton);
buttonCount ++ ;
jPanelInScrollPane.repaint();
jPanelInScrollPane.validate();

// validate the frame
validate();
}

public static void main(String args[]) {
DynamicScroll ds = new DynamicScroll();

ds.setSize(400,300);
ds.setVisible(true);
}
}
</sscce>

--
Andrew Thompson
http://www.athompson.info/andrew/

Message posted via JAVAKB.com
http://www.JAVAkb.com/Uwe/Forums.aspx/JAVA-gui/200709/1

From: Chanchal

Date: Thursday, September 27, 2007

wrote in message:
wrote in message:
.
>I have a JScrollPane on a JFrame. The JScrollPane contain a JPanel.On
>click of a JButton, i'm adding new JButtons to this JPanel, side by
>side.
..
>Starting from the 4th button which is added dynamically, the buttons
>goes outside the JScrollPane. I want the scrollbars of the JScrollPane
>to appear when the dynamically added buttons are outside the area of
>the JScrollPane so that I can scroll and view all the added JButtons.
>Kindly advice on how this can be done.
Layouts, layouts, *layouts*!
This example doesn't quite have the shape or size
you originally had, but it ostensibly works.
<sscce>
import JAVA.awt.*;
import JAVA.awt.event.*;
import JAVAx.swing.*;
import JAVAx.swing.border.*;
public class DynamicScroll extends JFrame implements ActionListener{
private int buttonCount = 0;
private JButton jButton1;
private JPanel jPanelInScrollPane;
private JScrollPane jScrollPane1;
public DynamicScroll() {
setDefaultCloseOperation( JFrame.DISPOSE_ON_CLOSE );
JPanel mainPanel = new JPanel( new BorderLayout(50,50) );
mainPanel.setBorder( new EmptyBorder(50,50,50,50) );
jPanelInScrollPane = new JPanel();
jScrollPane1 = new JScrollPane(jPanelInScrollPane);
jButton1 = new JButton("Add Button");
// have you not learned layouts yet?!
// 'null' layouts are the path to madness!
// the only time you should be setting a
// layout to null is for custom painting,
// and designing a new layout manager..
// considers - no, even then it is probably redundant
//getContentPane().setLayout(null);
jPanelInScrollPane.setLayout(new FlowLayout());
//jScrollPane1.setViewportView(jPanelInScrollPane);
mainPanel.add(jScrollPane1, BorderLayout.CENTER);
//jScrollPane1.setBounds(40, 40, 320, 80);
//jButton1.setText("Add Button");
jButton1.addActionListener(this);
mainPanel.add(jButton1, BorderLayout.SOUTH);
//jButton1.setBounds(150, 170, 120, 23);
setContentPane( mainPanel );
pack();
}
public void actionPerformed(ActionEvent evt) {
JButton newButton = new JButton("Button "+ buttonCount);
//newButton.setBounds( buttonCount * (100)+10, 5, 100, 50);
jPanelInScrollPane.add(newButton);
buttonCount ++ ;
jPanelInScrollPane.repaint();
jPanelInScrollPane.validate();
// validate the frame
validate();
}
public static void main(String args[]) {
DynamicScroll ds = new DynamicScroll();
ds.setSize(400,300);
ds.setVisible(true);
}}
</sscce>
--
Andrew Thompsonhttp://www.athompson.info/andrew/
Message posted via JAVAKB.comhttp://www.JAVAkb.com/Uwe/Forums.aspx/JAVA-gui/200709/1Dear Mr. Thompson,

Thanks for the input. But this isn't solving my problem. What
happens in this example is that when I click the button, the new
button is added at the center of the scrollpane because flowlayout is
used. I want it to come to the left most end. and when the second one
is added in your example the first one is moved a bit

<unit> (b) {binary} digit.

	The unit of information; the amount of information obtained by
	asking a yes-or-no question; a computational quantity that can
	take on one of two values, such as false and true or 0 and 1;
	the smallest unit of storage - sufficient to hold one bit.

	A bit is said to be "set" if its value is true or 1, and
	"reset" or "clear" if its value is false or 0.  One speaks of
	setting and clearing bits.  To {toggle} or "invert" a bit is
	to change it, either from 0 to 1 or from 1 to 0.

	The term "bit" first appeared in print in the computer-science
	sense in 1949, and seems to have been coined by the eminent
	statistician, {John Tukey}.  Tukey records that it evolved
	over a lunch table as a handier alternative to "bigit" or
	"binit".

	See also {flag}, {trit}, {mode bit}, {byte}, {word}.

	[{Jargon File}]

	(2002-01-22)

to left and the
newly added one is placed on the right of that. again because
flowlayout is used. but i don't want such movements. I want the first
button to be leftmost, the next one added to the right of that like
that. the button should be added only towards right, no movements to
the left. that's why (i think) I cannot use flowlayout here.

How can this might be implemented?

Thanks again

Chanchal

From: Ian Wilson

Date: Thursday, September 27, 2007

wrote in message:

Hi All,
I have a JScrollPane on a JFrame. The JScrollPane contain a JPanel.On
click of a JButton, i'm adding new JButtons to this JPanel, side by
side.
import JAVAx.swing.*;
import JAVA.awt.event.*;
public class DynamicScroll extends JFrame implements ActionListener{
private int buttonCount = 0;
private JButton jButton1;
private JPanel jPanelInScrollPane;
private JScrollPane jScrollPane1;
public DynamicScroll() {
jScrollPane1 = new JScrollPane();
jPanelInScrollPane = new JPanel();
jButton1 = new JButton();
getContentPane().setLayout(null);
jPanelInScrollPane.setLayout(null);
jScrollPane1.setViewportView(jPanelInScrollPane);
getContentPane().add(jScrollPane1);
jScrollPane1.setBounds(40, 40, 320, 80);
jButton1.setText("Add Button");
jButton1.addActionListener(this);
getContentPane().add(jButton1);
jButton1.setBounds(150, 170, 120, 23);
}
public void actionPerformed(ActionEvent evt) {
JButton newButton = new JButton("Button "+ buttonCount);
newButton.setBounds( buttonCount * (100)+10, 5, 100, 50);
jPanelInScrollPane.add(newButton);
buttonCount ++ ;
jPanelInScrollPane.repaint();
jPanelInScrollPane.validate();

jScrollPane1.validate();

}
public static void main(String args[]) {
DynamicScroll ds = new DynamicScroll();
ds.setSize(400,300);
ds.setVisible(true);
}
}
Starting from the 4th button which is added dynamically, the buttons
goes outside the JScrollPane. I want the scrollbars of the JScrollPane
to appear when the dynamically added buttons are outside the area of
the JScrollPane so that I can scroll and view all the added JButtons.
Kindly advice on how this can be done.

import JAVA.awt.FlowLayout;
import JAVA.awt.event.ActionEvent;
import JAVA.awt.event.ActionListener;

import JAVAx.swing.BoxLayout;
import JAVAx.swing.JButton;
import JAVAx.swing.JFrame;
import JAVAx.swing.JPanel;
import JAVAx.swing.JScrollPane;

public class DynamicScroll2 extends JPanel implements ActionListener{

private int buttonCount = 0;
private JButton jButton1;
private JPanel jPanelInScrollPane;
private JScrollPane jScrollPane1;

public static void main(String args[]) {
JFrame f = new JFrame("Dynamic Scroll 2");
DynamicScroll2 ds = new DynamicScroll2();
f.add(ds);
f.setSize(400,300);
f.setVisible(true);
}

public DynamicScroll2() {
jPanelInScrollPane = new JPanel();
jPanelInScrollPane.setLayout(
new BoxLayout(jPanelInScrollPane, BoxLayout.LINE_AXIS));

jScrollPane1 = new JScrollPane(jPanelInScrollPane);

jButton1 = new JButton("Add Button");
jButton1.addActionListener(this);

setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
add(jScrollPane1);
add(jButton1);
}

public void actionPerformed(ActionEvent evt) {
JButton newButton = new JButton("Button:"+ buttonCount);
newButton.setBounds( buttonCount * (100)+10, 5, 100, 50);
jPanelInScrollPane.add(newButton);
buttonCount ++ ;
jScrollPane1.validate();
}
}

From: Andrew Thompson

Date: Thursday, September 27, 2007

wrote in message:

[quoted text

1. Executable code, especially a "pure code" portion shared
	between multiple instances of a program running in a
	{multitasking} {operating system}.

	Compare {English}.

	2. Textual material in the mainstream sense; data in ordinary
	{ASCII} or {EBCDIC} representation (see {flat ASCII}).  "Those
	are text files; you can review them using the editor."

	These two contradictory senses confuse hackers too.

	[{Jargon File}]

	(1995-03-16)

clipped - 84 lines]

Please *trim* when replying!

Dear Mr. Thompson,
Thanks for the input. But this isn't solving my problem. What
happens in this example is that when I click the button, the new
button is added at the center of the scrollpane because flowlayout is
used. I want it to come to the left most end.

Did you try RTFM?
<http://JAVA.sun.com/JAVAse/6/docs/api/JAVA/awt/FlowLayout.html#FlowLayout(int
)>

--
Andrew Thompson
http://www.athompson.info/andrew/

Message posted via JAVAKB.com
http://www.JAVAkb.com/Uwe/Forums.aspx/JAVA-gui/200709/1

From: Roedy Green

Date: Friday, September 28, 2007

On Thu, 27 Sep 2007 07:36:30 -0700, Chanchal
wrote in message, quoted or indirectly quoted someone
who said :

i cannot use flowlayout here.

FlowLayout gives you very little control

<character> (Or "ctrl", "^") One (or a pair) of {modifier
	keys} found on all modern {keyboards}.  If the control key is
	held down while pressing and releasing certain other keys then
	a "{control character}" is generated, e.g. holding control and
	hitting "A" generates control-A ({ASCII} code 1).  The ASCII
	code for the control character is generally 64 less than that
	for the unmodified character.

	The control key does not generate any character on its own but
	most modern keyboards and {operating systems} allow a program
	to tell whether each of the individual keys on the keyboard
	(including modifier keys) is pressed at any time.

	Control characters mostly have some kind of "non-printing"
	effect on the output such as ringing the bell (Control-G) or
	advancing to the next line (Control-J).  Most have alternative
	names suggesting these functions (Bell, Line Feed, etc.).

	See {ASCII character table}.

	(1997-07-10)

over positioning. See the
other layouts at http://mindprod.com/jgloss/layout.html
--
Roedy Green

A language proposed by Cii {Honeywell-Bull} to meet the DoD
	{Ironman} requirements which led to {Ada}.  This language won
	in 1979.

	["On the GREEN Language Submitted to the DoD", E.W. Dijkstra,
	SIGPLAN Notices 13(10):16-21 (Oct 1978)].

	(1994-12-02)

Canadian Mind Products
The JAVA Glossary
http://mindprod.com

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