javax.swing
Class JScrollPane

java.lang.Object   
  java.awt.Component   
      java.awt.Container   
          javax.swing.JComponent   
              javax.swing.JScrollPane

All Implemented Interfaces:

ImageObserver , MenuContainer , Serializable , Accessible , ScrollPaneConstants

public class JScrollPane
extends JComponent   
implements ScrollPaneConstants   , Accessible   

Provides a scrollable view of a lightweight component. A JScrollPane manages a viewport, optional vertical and horizontal scroll bars, and optional row and column heading viewports. You can find task-oriented documentation of JScrollPane in How to Use Scroll Panes, a section in The Java Tutorial. Note that JScrollPane does not support heavyweight components.

The JViewport provides a window, or "viewport" onto a data source -- for example, a text file. That data source is the "scrollable client" (aka data model) displayed by the JViewport view. A JScrollPane basically consists of JScrollBars, a JViewport, and the wiring between them, as shown in the diagram at right.

In addition to the scroll bars and viewport, a JScrollPane can have a column header and a row header. Each of these is a JViewport object that you specify with setRowHeaderView, and setColumnHeaderView. The column header viewport automatically scrolls left and right, tracking the left-right scrolling of the main viewport. (It never scrolls vertically, however.) The row header acts in a similar fashion.

By default, the corners are empty. You can put a component into a corner using setCorner, in case you there is some function or decoration you would like to add to the scroll pane. The size of corner components is entirely determined by the size of the headers and scroll bars that surround them.

To add a border around the main viewport, you can use setViewportBorder. (Of course, you can also add a border around the whole scroll pane using setBorder.)

A common operation to want to do is to set the background color that will be used if the main viewport view is smaller than the viewport, or is not opaque. This can be accomplished by setting the background color of the viewport, via scrollPane.getViewport().setBackground(). The reason for setting the color of the viewport and not the scrollpane is that by default JViewport is opaque which, among other things, means it will completely fill in its background using its background color. Therefore when JScrollPane draws its background the viewport will usually draw over it.

By default JScrollPane uses ScrollPaneLayout to handle the layout of its child Components. ScrollPaneLayout determines the size to make the viewport view in one of two ways:

1. If the view implements Scrollable a combination of getPreferredScrollableViewportSize, getScrollableTracksViewportWidth and getScrollableTracksViewportHeightis used, otherwise
2. getPreferredSize is used.

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans^TM has been added to the java.beans package. Please see XMLEncoder .

See Also:

JScrollBar , JViewport , ScrollPaneLayout , Scrollable , Component.getPreferredSize() , setViewportView(java.awt.Component) , setRowHeaderView(java.awt.Component) , setColumnHeaderView(java.awt.Component) , setCorner(java.lang.String, java.awt.Component) , setViewportBorder(javax.swing.border.Border) , Serialized Form

Nested Class Summary

protected class	JScrollPane.AccessibleJScrollPane This class implements accessibility support for the JScrollPane class.
protected class	JScrollPane.ScrollBar By default JScrollPane creates scrollbars that are instances of this class.

Nested classes/interfaces inherited from class javax.swing.JComponent

JComponent.AccessibleJComponent

Nested classes/interfaces inherited from class java.awt.Container

Container.AccessibleAWTContainer

Nested classes/interfaces inherited from class java.awt.Component

Component.AccessibleAWTComponent , Component.BltBufferStrategy , Component.FlipBufferStrategy

Field Summary

protected JViewport	columnHeader The column header child.
protected JScrollBar	horizontalScrollBar The scrollpane's horizontal scrollbar child.
protected int	horizontalScrollBarPolicy The display policy for the horizontal scrollbar.
protected Component	lowerLeft The component to display in the lower left corner.
protected Component	lowerRight The component to display in the lower right corner.
protected JViewport	rowHeader The row header child.
protected Component	upperLeft The component to display in the upper left corner.
protected Component	upperRight The component to display in the upper right corner.
protected JScrollBar	verticalScrollBar The scrollpane's vertical scrollbar child.
protected int	verticalScrollBarPolicy The display policy for the vertical scrollbar.
protected JViewport	viewport The scrollpane's viewport child.

Fields inherited from class javax.swing.JComponent

accessibleContext , listenerList , TOOL_TIP_TEXT_KEY , ui , UNDEFINED_CONDITION , WHEN_ANCESTOR_OF_FOCUSED_COMPONENT , WHEN_FOCUSED , WHEN_IN_FOCUSED_WINDOW

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT , CENTER_ALIGNMENT , LEFT_ALIGNMENT , RIGHT_ALIGNMENT , TOP_ALIGNMENT

Fields inherited from interface javax.swing.ScrollPaneConstants

COLUMN_HEADER , HORIZONTAL_SCROLLBAR , HORIZONTAL_SCROLLBAR_ALWAYS , HORIZONTAL_SCROLLBAR_AS_NEEDED , HORIZONTAL_SCROLLBAR_NEVER , HORIZONTAL_SCROLLBAR_POLICY , LOWER_LEADING_CORNER , LOWER_LEFT_CORNER , LOWER_RIGHT_CORNER , LOWER_TRAILING_CORNER , ROW_HEADER , UPPER_LEADING_CORNER , UPPER_LEFT_CORNER , UPPER_RIGHT_CORNER , UPPER_TRAILING_CORNER , VERTICAL_SCROLLBAR , VERTICAL_SCROLLBAR_ALWAYS , VERTICAL_SCROLLBAR_AS_NEEDED , VERTICAL_SCROLLBAR_NEVER , VERTICAL_SCROLLBAR_POLICY , VIEWPORT

Fields inherited from interface java.awt.image.ImageObserver

ABORT , ALLBITS , ERROR , FRAMEBITS , HEIGHT , PROPERTIES , SOMEBITS , WIDTH

Constructor Summary

JScrollPane ()
Creates an empty (no viewport view) JScrollPane where both horizontal and vertical scrollbars appear when needed.

JScrollPane (Component view)
Creates a JScrollPane that displays the contents of the specified component, where both horizontal and vertical scrollbars appear whenever the component's contents are larger than the view.

JScrollPane (Component view, int vsbPolicy, int hsbPolicy)
Creates a JScrollPane that displays the view component in a viewport whose view position can be controlled with a pair of scrollbars.

JScrollPane (int vsbPolicy, int hsbPolicy)
Creates an empty (no viewport view) JScrollPane with specified scrollbar policies.

Method Summary

JScrollBar	createHorizontalScrollBar () Returns a JScrollPane.ScrollBar by default.
JScrollBar	createVerticalScrollBar () Returns a JScrollPane.ScrollBar by default.
protected JViewport	createViewport () Returns a new JViewport by default.
AccessibleContext	getAccessibleContext () Gets the AccessibleContext associated with this JScrollPane.
JViewport	getColumnHeader () Returns the column header.
Component	getCorner (String key) Returns the component at the specified corner.
JScrollBar	getHorizontalScrollBar () Returns the horizontal scroll bar that controls the viewport's horizontal view position.
int	getHorizontalScrollBarPolicy () Returns the horizontal scroll bar policy value.
JViewport	getRowHeader () Returns the row header.
ScrollPaneUI	getUI () Returns the look and feel (L&F) object that renders this component.
String	getUIClassID () Returns the suffix used to construct the name of the L&F class used to render this component.
JScrollBar	getVerticalScrollBar () Returns the vertical scroll bar that controls the viewports vertical view position.
int	getVerticalScrollBarPolicy () Returns the vertical scroll bar policy value.
JViewport	getViewport () Returns the current JViewport.
Border	getViewportBorder () Returns the Border object that surrounds the viewport.
Rectangle	getViewportBorderBounds () Returns the bounds of the viewport's border.
boolean	isValidateRoot () Overridden to return true so that any calls to revalidate on any descendants of this JScrollPane will cause the entire tree beginning with this JScrollPane to be validated.
boolean	isWheelScrollingEnabled () Indicates whether or not scrolling will take place in response to the mouse wheel.
protected String	paramString () Returns a string representation of this JScrollPane.
void	setColumnHeader (JViewport columnHeader) Removes the old columnHeader, if it exists.
void	setColumnHeaderView (Component view) Creates a column-header viewport if necessary, sets its view, and then adds the column-header viewport to the scrollpane.
void	setComponentOrientation (ComponentOrientation co) Sets the orientation for the vertical and horizontal scrollbars as determined by the ComponentOrientation argument.
void	setCorner (String key, Component corner) Adds a child that will appear in one of the scroll panes corners, if there's room.
void	setHorizontalScrollBar (JScrollBar horizontalScrollBar) Adds the scrollbar that controls the viewport's horizontal view position to the scrollpane.
void	setHorizontalScrollBarPolicy (int policy) Determines when the horizontal scrollbar appears in the scrollpane.
void	setLayout (LayoutManager layout) Sets the layout manager for this JScrollPane.
void	setRowHeader (JViewport rowHeader) Removes the old rowHeader, if it exists.
void	setRowHeaderView