JScrollPane Visibility

Hey,
I'm having some issues with setVisible on JScrollPanes.
Basically I'm writing a little class that's storing settings using java.util.Properties.
These settings are checked on load to see if it should display some certain buttons, and a JScrollPane.
I've also included a JMenu with checkbox items to toggle visibility of these buttons/JScrollPane during runtime.
Now to the problem, when I launch the class with the JScrollPane disabled in configuration I can't seem to make it visible again.
The setVisible(true); line is being run, as I've printlned the object on change. But it's just not appearing on screen.
When the class is run with the JScrollPane enabled in configuration it runs fine, and changes visibility on demand.
Heres a small example snippet:
Properties config = new Properties();
config.load(new FileInputStream("configfile.cfg));
if (config.get("showScroll")!=null) {
    if (config.get("showScroll").equals("0") {
        scrollPane.setVisible(false);
    } else {
        scrollPane.setVisible(true);
} else {
    config.setProperty("showScroll","1");
    scrollPane.setVisible(true);
}Then the toggle button changes setVisible(); between true/false and config.setProperty("showScroll","1/0");.
So basically if at runtime "showScroll" = "0" the scrollPane won't be visible, and the toggle button won't make it visible even though it is changing the state.
If "showScroll" = "1" the scrollPane will be visible, and the toggle button will toggle it between visible and invisible without any hassles.
Sorry if this post is mumbled, 3am here and I'm a bit tired.
Thanks in advance.

Ahh great, thanks heaps.
I came so close as well, I had actually tried repaint() with no luck.
validate(); worked a treat :)

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Hi weebib ,
pls find some working code which shous my problame .
you can see its coming to column 'B'. but i want it to show from column 'A' .
sample working code : =
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import java.awt.event.*;
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int NO_OF_ROWS = 64;
int NO_OF_COLUMNS = 65;
Vector vColumnNames ;
myTable(){
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================
pls do reply back if i am doing something wrong.
== Gavin

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} I hope this helps you get an idea of what I am trying to do and what the problem might be. Any help would be really appreciated. I have spent hours on this and I have no idea why it doesn't work.
The actual code is much bigger, so if you need any extra information, please tell me.

HelloPanel should provide a "public Dimension getPreferredSize()" method.
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Hi camickr
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Now I'm still confused on how to solve the original problem.
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That's a tricky one.
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I havent been able to test the above suggestions yet so I cant tell if it will work.
The problem is really how to tell JScrollPane how big the scrolling area is.
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I want to decide myself which data to paint.
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This is a very common mistake. When you put a JPanel in a scrollpane, the scrollpane will use the panel's preferred size to determine if scrolling is needed or not. If the panel is using a LayoutManager this is generally done for you automatically. But in your case you set the layout to null, and then it is your responsibility to make sure that the getPreferredSize() method of the panel returns the correct size.
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            public Dimension getPreferredSize() {
                return getSize();
    }Then the scrollbars will appear if you make the frame smaller.
But what I really suggest is that you use a LayoutManager.

JScrollPane: Contents not visible

I am having trouble using JScrollPane. My situation is this ...
I have an abstract class (PanelSupport) that extends JPanel and a class (TaskPane) that extends this abstract class. I want to add the class TaskPane to a JScrollPane but when I do this the scroll pane appears empty.
I previously had the TaskPane being displayed without a scroll pane and it worked a treat but as soon as I introduce the JScollPane and insert the TaskPane into that I see nothing in the scroll pane. Any clues as to why?

I am having trouble using JScrollPane. My situation
is this ...
I have an abstract class (PanelSupport) that extends
JPanel and a class (TaskPane) that extends this
abstract class. I want to add the class TaskPane to a
JScrollPane but when I do this the scroll pane appears
empty.
I previously had the TaskPane being displayed without
a scroll pane and it worked a treat but as soon as I
introduce the JScollPane and insert the TaskPane into
that I see nothing in the scroll pane. Any clues as
to why?Just a stab in the dark but if you are not already doing this, try:
yourscrollpane.getViewport().add(yourpanel);

How to add a JScrollPane in a JPanel

I have a JPanel (layout = null, size = 200*400).
I would like to add a JScrollPane, that sizes 100*100 and that contains an other JPanel, at the location 0,200 in the first JPanel. I would like too that the JScrollBar is always visible.
How is it possible ?

The scrollbars will appear automatically when the preferred size of the panel is greater than the size of the scroll pane. So you probably need to add:
panel.setPreferredSize(...);
Of course if you use LayoutManagers, instead of a null layout, then this is done automatically for you.
If you want the scroll bars to appear all the time then read the JScrollPane API.

Varying size of JScrollPane

Hi.
I hope you can help me figure out what's going on. I have a component that I've written that should display buttons vertically (it's a basis for an OutlookBar styled component).
The component is based on a JPanel that is put in a JScrollPane and the buttons are added to the JPanel. The JPanel has a VerticalFlowLayout (a custom layout class).
Now for the problem: Every time I adjust the size of the component so that a scroll bar should appear, the getPreferredSize() method of the JScrollPane returns a width that is lesser than it returns when the scroll bar is not visible! The weird thing is that the difference in the width is exactly the width of the scroll bar... but it doesn't make much sense since the width that is returned when the scroll bar is visible is less than the width that is returned when the scroll bar is not visible (it would make sense to have it the other way around!).
Since my component needs to keep a consistent width this behavior is extremely annoying! Below you can find the code for the panel (and the needed layout) if you'd like to try this out, any help will be greatly appreciated:
import javax.swing.*;
import javax.swing.plaf.ComponentUI;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
* A panel that contains a set of operations that are displayed under a common
* category name on a <code>OutlookBar</code>.
* @version Revision:$ Date:$
public class OutlookBarCategoryPanel extends JPanel
    protected JPanel m_contentPanel = new JPanel( new VerticalFlowLayout( 5 ) );
    private JScrollPane m_contentScrollPane = new JScrollPane( m_contentPanel,
                                                    JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED,
                                                    JScrollPane.HORIZONTAL_SCROLLBAR_NEVER );
     * Constructs a new <tt>OutlookBarCategoryPanel</tt> that is initially empty.
    public OutlookBarCategoryPanel()
        super( new BorderLayout() );
        m_contentPanel.setBackground( SystemColor.control );
        super.add( m_contentScrollPane, BorderLayout.CENTER );
     * If the <code>preferredSize</code> has been set to a
     * non-<code>null</code> value just returns it.
     * If the UI delegate's <code>getPreferredSize</code>
     * method returns a non <code>null</code> value then return that;
     * otherwise defer to the component's layout manager.
     * @return the value of the <code>preferredSize</code> property
     * @see #setPreferredSize
     * @see ComponentUI
    public Dimension getPreferredSize()
        Dimension size = super.getPreferredSize();
        if( size.width < m_contentScrollPane.getPreferredSize().width )
            size.width = m_contentScrollPane.getPreferredSize().width;
        return size;
     * Appends the specified component to the end of this container.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * Note: If a component has been added to a container that
     * has been displayed, <code>validate</code> must be
     * called on that container to display the new component.
     * If multiple components are being added, you can improve
     * efficiency by calling <code>validate</code> only once,
     * after all the components have been added.
     * @param     comp   the component to be added
     * @see #addImpl
     * @see #validate
     * @see #revalidate
     * @return    the component argument
    public Component add( Component comp )
        return m_contentPanel.add( comp );
     * Adds the specified component to the end of this container.
     * Also notifies the layout manager to add the component to
     * this container's layout using the specified constraints object.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * Note: If a component has been added to a container that
     * has been displayed, <code>validate</code> must be
     * called on that container to display the new component.
     * If multiple components are being added, you can improve
     * efficiency by calling <code>validate</code> only once,
     * after all the components have been added.
     * @param     comp the component to be added
     * @param     constraints an object expressing
     *                  layout contraints for this component
     * @see #addImpl
     * @see #validate
     * @see #revalidate
     * @see       LayoutManager
     * @since     JDK1.1
    public void add( Component comp, Object constraints )
        m_contentPanel.add( comp );
     * Adds the specified component to this container with the specified
     * constraints at the specified index. Also notifies the layout
     * manager to add the component to the this container's layout using
     * the specified constraints object.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * Note: If a component has been added to a container that
     * has been displayed, <code>validate</code> must be
     * called on that container to display the new component.
     * If multiple components are being added, you can improve
     * efficiency by calling <code>validate</code> only once,
     * after all the components have been added.
     * @param comp the component to be added
     * @param constraints an object expressing layout contraints for this
     * @param index the position in the container's list at which to insert
     * the component; <code>-1</code> means insert at the end
     * component
     * @see #addImpl
     * @see #validate
     * @see #revalidate
     * @see #remove
     * @see LayoutManager
    public void add( Component comp, Object constraints, int index )
        m_contentPanel.add( comp, index );
     * Adds the specified component to this container at the given
     * position.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * Note: If a component has been added to a container that
     * has been displayed, <code>validate</code> must be
     * called on that container to display the new component.
     * If multiple components are being added, you can improve
     * efficiency by calling <code>validate</code> only once,
     * after all the components have been added.
     * @param     comp   the component to be added
     * @param     index    the position at which to insert the component,
     *                   or <code>-1</code> to append the component to the end
     * @return    the component <code>comp</code>
     * @see #addImpl
     * @see #remove
     * @see #validate
     * @see #revalidate
    public Component add( Component comp, int index )
        return m_contentPanel.add( comp, index );
     * Adds the specified component to this container.
     * This is a convenience method for {@link #addImpl}.
     * <p>
     * This method is obsolete as of 1.1. Please use the
     * method <code>add(Component, Object)</code> instead.
     * @see add(Component, Object)
    public Component add( String name, Component comp )
        return m_contentPanel.add( name, comp );
     * Removes the specified button from the panel. The reference that is sent as
     * a parameter needs to point to the same instance as the button that should actually
     * be removed (in other words, this method will not perform an equal() comparison).
     * @param button    a reference to the button that should be removed.
    public void remove( OutlookBarOperationButton button )
        m_contentPanel.remove( button );
     * Removes all operations that have the specified caption.
     * @param caption   the caption of the operation(s) that should be removed.
    public void removeOperation( String caption )
        Component[] components = m_contentPanel.getComponents();
        for( int i=0; i<components.length; i++ )
            Component component = components;
if( component != null && component instanceof AbstractButton )
if( ((AbstractButton)component).getText().equals( caption ) )
m_contentPanel.remove( i );
public static void main( String[] args )
JFrame frame = new JFrame( "OutlookBarCategorButton" );
frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
frame.getContentPane().setLayout( new BorderLayout() );
OutlookBarCategoryPanel obcp = new OutlookBarCategoryPanel();
obcp.add( new OutlookBarOperationButton( "foo", new ImageIcon( "images/History24.gif" ) ) );
obcp.add( new OutlookBarOperationButton( "bar", new ImageIcon( "images/Help24.gif" ) ) );
obcp.add( new OutlookBarOperationButton( "foobar", new ImageIcon( "images/Cut24.gif" ) ) );
obcp.add( new OutlookBarOperationButton( "index 2", new ImageIcon( "images/isl_faninn.png" ) ), 2 );
frame.getContentPane().add( obcp, BorderLayout.WEST );
frame.pack();
frame.show();
And here is the code for the VerticalFlowLayout class:
import java.awt.*;
* A layout manager that works like the default layout manager in swing
* (FlowLayout) except that it arranges its components vertically instead
* of horizontally.
* @version $Revision: 1.1 $ $Date: 2003/03/11 13:37:38 $
public class VerticalFlowLayout implements LayoutManager
    private int m_vgap;
     * Creates a new instance of the class with an initial vertical gap of 0
     * pixels.
    public VerticalFlowLayout()
        this( 0 );
     * Creates a new instance of the class with an initial vertical gap of
     * the specified number of pixels.
     * @param vgap the number of pixels to use as a gap between
     *              components
    public VerticalFlowLayout( int vgap )
        m_vgap = vgap;
     * Lays out the container in the specified panel.
     * @param theParent the component which needs to be laid out
    public void layoutContainer( Container theParent )
        Insets insets = theParent.getInsets();
        int w = theParent.getSize().width - insets.left - insets.right;
        int numComponents = theParent.getComponentCount();
        if( numComponents == 0 )
            return;
        int y = insets.top;
        int x = insets.left;
        for( int i = 0; i < numComponents; ++i )
            Component c = theParent.getComponent(i);
            if( c.isVisible() )
                Dimension d = c.getPreferredSize();
                c.setBounds( x, y, w, d.height );
                y += d.height + m_vgap;
     * Calculates the minimum size dimensions for the specified
     * panel given the components in the specified parent container.
     * @param theParent the component to be laid out
     * @see #preferredLayoutSize
    public Dimension minimumLayoutSize( Container theParent )
        Insets insets = theParent.getInsets();
        int maxWidth = 0;
        int totalHeight = 0;
        int numComponents = theParent.getComponentCount();
        for( int i = 0; i < numComponents; ++i )
            Component c = theParent.getComponent( i );
            if( c.isVisible() )
                Dimension cd = c.getMinimumSize();
                maxWidth = Math.max( maxWidth, cd.width );
                totalHeight += cd.height;
        Dimension td = new Dimension( maxWidth + insets.left + insets.right,
                totalHeight + insets.top + insets.bottom + m_vgap * numComponents );
        return td;
     * If the layout manager uses a per-component string,
     * adds the component <code>comp</code> to the layout,
     * associating it
     * with the string specified by <code>name</code>.
     * @param name the string to be associated with the component
     * @param comp the component to be added
    public void addLayoutComponent( String name, Component comp )
     * Removes the specified component from the layout.
     * @param comp the component to be removed
    public void removeLayoutComponent( Component comp )
     * Calculates the preferred size dimensions for the specified
     * panel given the components in the specified parent container.
     * @param theParent the component to be laid out
     * @see #minimumLayoutSize
    public Dimension preferredLayoutSize( Container theParent )
        Insets insets = theParent.getInsets();
        int maxWidth = 0;
        int totalHeight = 0;
        int numComponents = theParent.getComponentCount();
        for( int i = 0; i < numComponents; ++i )
            Component c = theParent.getComponent( i );
            if( c.isVisible() )
                Dimension cd = c.getPreferredSize();
                maxWidth = Math.max( maxWidth, cd.width );
                totalHeight += cd.height;
        Dimension td = new Dimension( maxWidth + insets.left + insets.right,
                totalHeight + insets.top + insets.bottom + m_vgap * numComponents );
        return td;

You can use calligraphy/ art brush strokes, can you not? Some of them come with AI and you can find quite a few on ze interweb. You could even create your own, if need be.
Mylenium

How to find out if JTable's selected row is visible?

Hello there,
Given:
a JTable is inserted into a JScrollPane and the number of rows in the table is greater than the vieport size.
A random row within the table gets programmatically selected.
How to find out if the selected row is visible in a JTable visible area?
Your help will be greatly appreciated.
Tim

That will make the row visible, but not answer whether it was visible
in the first place. Try something like:
public boolean isRowVisible( JTable table, int row ) {
    Rectangle rect = table.getBounds();
    int rowHeight = table.getRowHeight();
    int viewHeight = table.getParent().getHeight();
    int max = rect.y - viewHeight + 1;
    int rowPos = - rowHeight * row;
    return ( rect.y >= rowPos && rowPos > max );
}assuming all rows have the same height.
: jay

JScrollPane not scrolling to the end of JTable

Hello,
I put a table in a scroll pane, and add the scroll pane to a panel. The problem is the scroll pane does not scroll to the end of the table, it always lets me view only the first 37 rows of the table, regardless of how many rows the table actually has. Basically, the scroll pane thinks the table has exactly the same height, no matter how many lines it has. Why is this happening?
The code is something like
model = new SearchResultTableModel(false, null, null);
table = new ResultTable(model);
scrollPane = new JScrollPane(table);
mainBox.add(scrollPane);
If this is important, the table is a bit more complicated, I subclass JTable, use a custom TableModel, several types of cell renderers / editors, so maybe this is why it behaves so strange. How could I tell the scroll pane the table is actually larger?
Thank you very much, any ideas are highly appreciated,
Regards from Romania,
Adi

Hi,
fireTableDataChanged() is the easiest way to do it, but also that one, that forces JTable to rerender all visible cells, regardless the fact, that they are already displayed and would not need rerendering - if you add a row - for example row 7 - do fireTableRowsInserted(7,7); instead - so JTable will only render this single row if it is visible in the viewport. If you add a couple of rows, for example row 7 to 227, do fireTableRowsInserted(7,227); - always fire only the correct notifications accordingly to the changes you make, in order to keep the performance of JTable high.
greetings Marsian

JScrollPane Visibility

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