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Class com.sun.java.swing.JScrollBar

java.lang.Object
   |
   +----java.awt.Component
           |
           +----java.awt.Container
                   |
                   +----com.sun.java.swing.JComponent
                           |
                           +----com.sun.java.swing.JScrollBar

public class JScrollBar

extends JComponent

implements Adjustable, Accessible

Typically, as the position of the knob in the scrollbar changes a corresponding change is made to the position of the JViewPort on the underlying view, changing the contents of the JViewPort.

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 Swing1.0 applications. It will not be possible to load serialized Swing1.0 objects with future releases of Swing. The JDK1.2 release of Swing will be the compatibility baseline for the serialized form of Swing objects.

See Also:

JScrollPane

blockIncrement

model

The model that represents the scrollbar's minimum, maximum, extent (aka "visibleAmount") and current value.

orientation

unitIncrement

JScrollBar()

Creates a vertical scrollbar with the following initial values:

 minimum = 0 
 maximum = 100 
 value = 0
 extent = 10
 

JScrollBar(int)

Creates a scrollbar with the specified orientation and the following initial values:

 minimum = 0 
 maximum = 100 
 value = 0
 extent = 10
 

JScrollBar(int, int, int, int, int)

Creates a scrollbar with the specified orientation, value, extent, mimimum, and maximum.

addAdjustmentListener(AdjustmentListener)

Adds an AdjustmentListener.

fireAdjustmentValueChanged(int, int, int)

getAccessibleContext()

Get the AccessibleContext associated with this JComponent

getBlockIncrement()

For backwards compatibility with java.awt.Scrollbar.

getBlockIncrement(int)

Returns the amount to change the scrollbar's value by, given a block (usually "page") up/down request.

getMaximum()

The maximum value of the scrollbar is maximum - extent.

getMaximumSize()

The scrollbar is flexible along it's scrolling axis and rigid along the other axis.

getMinimum()

Returns the minimum value supported by the scrollbar (usually zero).

getMinimumSize()

The scrollbar is flexible along it's scrolling axis and rigid along the other axis.

getModel()

Returns data model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent.

getOrientation()

Returns the component's orientation (horizontal or vertical).

getUI()

Returns the delegate that implements the look and feel for this component.

getUIClassID()

Returns the name of the LookAndFeel class for this component.

getUnitIncrement()

For backwards compatibility with java.awt.Scrollbar.

getUnitIncrement(int)

Returns the amount to change the scrollbar's value by, given a unit up/down request.

getValue()

Returns the scrollbar's value.

getValueIsAdjusting()

True if the scrollbar knob is being dragged.

getVisibleAmount()

Returns the scrollbar's extent, aka its "visibleAmount".

removeAdjustmentListener(AdjustmentListener)

Removes an AdjustmentEvent listener.

setBlockIncrement(int)

Sets the blockIncrement property.

setEnabled(boolean)

Enables the component so that the knob position can be changed.

setMaximum(int)

Sets the model's maximum property.

setMinimum(int)

Sets the model's minimum property.

setModel(BoundedRangeModel)

Sets the model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent.

setOrientation(int)

Set the scrollbar's orientation to either VERTICAL or HORIZONTAL.

setUnitIncrement(int)

Sets the unitIncrement property.

setValue(int)

Sets the scrollbar's value.

setValueIsAdjusting(boolean)

Sets the model's valueIsAdjusting property.

setValues(int, int, int, int)

Sets the four BoundedRangeModel properties after forcing the arguments to obey the usual constraints:

 minimum <= value <= value+extent <= maximum
 

setVisibleAmount(int)

Set the model's extent property.

updateUI()

 protected BoundedRangeModel model

The model that represents the scrollbar's minimum, maximum, extent (aka "visibleAmount") and current value.

See Also:

setModel

 protected int orientation

See Also:

setOrientation

 protected int unitIncrement

See Also:

setUnitIncrement

 protected int blockIncrement

See Also:

setBlockIncrement

 public JScrollBar(int orientation,
                   int value,
                   int extent,
                   int min,
                   int max)

Creates a scrollbar with the specified orientation, value, extent, mimimum, and maximum. The "extent" is the size of the viewable area. It is also known as the "visible amount".

Note: Use setBlockIncrement to set the block increment to a size slightly smaller than the view's extent. That way, when the user jumps the knob to an adjacent position, one or two lines of the original contents remain in view.

Throws: IllegalArgumentException

if orientation is not one of VERTICAL, HORIZONTAL

See Also:

setOrientation, setValue, setVisibleAmount, setMinimum, setMaximum

 public JScrollBar(int orientation)

Creates a scrollbar with the specified orientation and the following initial values:

 minimum = 0 
 maximum = 100 
 value = 0
 extent = 10
 

 public JScrollBar()

Creates a vertical scrollbar with the following initial values:

 minimum = 0 
 maximum = 100 
 value = 0
 extent = 10
 

 public ScrollBarUI getUI()

Returns the delegate that implements the look and feel for this component.

See Also:

setUI

 public void updateUI()

Overrides:

updateUI in class JComponent

See Also:

updateUI

 public String getUIClassID()

Returns the name of the LookAndFeel class for this component.

Returns:

"ScrollBarUI"

Overrides:

getUIClassID in class JComponent

See Also:

getUIClassID, getUI

 public int getOrientation()

Returns the component's orientation (horizontal or vertical).

Returns:

VERTICAL or HORIZONTAL

See Also:

setOrientation, getOrientation

 public void setOrientation(int orientation)

Set the scrollbar's orientation to either VERTICAL or HORIZONTAL.

Throws: IllegalArgumentException

if orientation is not one of VERTICAL, HORIZONTAL

See Also:

getOrientation

 public BoundedRangeModel getModel()

Returns data model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent.

See Also:

setModel

 public void setModel(BoundedRangeModel newModel)

Sets the model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent.

See Also:

getModel

 public int getUnitIncrement(int direction)

Returns the amount to change the scrollbar's value by, given a unit up/down request. A ScrollBarUI implementation typically calls this method when the user clicks on a scrollbar up/down arrow and uses the result to update the scrollbar's value. Subclasses my override this method to compute a value, e.g. the change required to scroll up or down one (variable height) line text or one row in a table.

The JScrollPane component creates scrollbars (by default) that override this method and delegate to the viewports Scrollable view, if it has one. The Scrollable interface provides a more specialized version of this method.

Parameters:

direction - is -1 or 1 for up/down respectively

Returns:

the value of the unitIncrement property

See Also:

setUnitIncrement, setValue, getScrollableUnitIncrement

 public void setUnitIncrement(int unitIncrement)

Sets the unitIncrement property.

See Also:

getUnitIncrement

 public int getBlockIncrement(int direction)

Returns the amount to change the scrollbar's value by, given a block (usually "page") up/down request. A ScrollBarUI implementation typically calls this method when the user clicks above or below the scrollbar "knob" to change the value up or down by large amount. Subclasses my override this method to compute a value, e.g. the change required to scroll up or down one paragraph in a text document.

The JScrollPane component creates scrollbars (by default) that override this method and delegate to the viewports Scrollable view, if it has one. The Scrollable interface provides a more specialized version of this method.

Parameters:

direction - is -1 or 1 for up/down respectively

Returns:

the value of the blockIncrement property

See Also:

setBlockIncrement, setValue, getScrollableBlockIncrement

 public void setBlockIncrement(int blockIncrement)

Sets the blockIncrement property.

See Also:

setBlockIncrement

 public int getUnitIncrement()

For backwards compatibility with java.awt.Scrollbar.

See Also:

getUnitIncrement, getUnitIncrement

 public int getBlockIncrement()

For backwards compatibility with java.awt.Scrollbar.

See Also:

getBlockIncrement, getBlockIncrement

 public int getValue()

Returns the scrollbar's value.

Returns:

the model's value property

See Also:

setValue

 public void setValue(int value)

Sets the scrollbar's value. This method just forwards the value to the model.

See Also:

getValue, setValue

 public int getVisibleAmount()

Returns the scrollbar's extent, aka its "visibleAmount". In many scrollbar look and feel implementations the size of the scrollbar "knob" or "thumb" is proportional to the extent.

Returns:

the value of the model's extent property

See Also:

setVisibleAmount

 public void setVisibleAmount(int extent)

Set the model's extent property.

See Also:

getVisibleAmount, setExtent

 public int getMinimum()

Returns the minimum value supported by the scrollbar (usually zero).

Returns:

the value of the model's minimum property

See Also:

setMinimum

 public void setMinimum(int minimum)

Sets the model's minimum property.

See Also:

getMinimum, setMinimum

 public int getMaximum()

The maximum value of the scrollbar is maximum - extent.

Returns:

the value of the model's maximum property

See Also:

setMaximum

 public void setMaximum(int maximum)

Sets the model's maximum property. Note that the scrollbar's value can only be set to maximum - extent.

See Also:

getMaximum, setMaximum

 public boolean getValueIsAdjusting()

True if the scrollbar knob is being dragged.

Returns:

the value of the model's valueIsAdjusting property

See Also:

setValueIsAdjusting

 public void setValueIsAdjusting(boolean b)

Sets the model's valueIsAdjusting property. Scrollbar look and feel implementations should set this property to true when a knob drag begins, and to false when the drag ends. The scrollbar model will not generate ChangeEvents while valueIsAdjusting is true.

See Also:

getValueIsAdjusting, setValueIsAdjusting

 public void setValues(int newValue,
                       int newExtent,
                       int newMin,
                       int newMax)

Sets the four BoundedRangeModel properties after forcing the arguments to obey the usual constraints:

 minimum <= value <= value+extent <= maximum
 

See Also:

setRangeProperties, setValue, setVisibleAmount, setMinimum, setMaximum

 public void addAdjustmentListener(AdjustmentListener l)

Adds an AdjustmentListener. Adjustment listeners are notified each time the scrollbar's model changes. Adjustment events are provided for backwards compatability with java.awt.Scrollbar.

Note that the AdjustmentEvents type property will always have a placeholder value of AdjustmentEvent.TRACK because all changes to a BoundedRangeModels value are considered equivalent. To change the value of a BoundedRangeModel one just sets its value property, i.e. model.setValue(123). No information about the origin of the change, e.g. it's a block decrement, is provided. We don't try fabricate the origin of the change here.

Parameters:

l - the AdjustmentLister to add

See Also:

removeAdjustmentListener, addChangeListener

 public void removeAdjustmentListener(AdjustmentListener l)

Removes an AdjustmentEvent listener.

Parameters:

l - the AdjustmentLister to remove

See Also:

addAdjustmentListener

 protected void fireAdjustmentValueChanged(int id,
                                           int type,
                                           int value)

 public Dimension getMinimumSize()

The scrollbar is flexible along it's scrolling axis and rigid along the other axis.

Overrides:

getMinimumSize in class JComponent

 public Dimension getMaximumSize()

The scrollbar is flexible along it's scrolling axis and rigid along the other axis.

Overrides:

getMaximumSize in class JComponent

 public void setEnabled(boolean x)

Enables the component so that the knob position can be changed. When the disabled, the knob position cannot be changed.

Parameters:

b - a boolean value, where true enables the component and false disables it

Overrides:

setEnabled in class Component

 public AccessibleContext getAccessibleContext()

Get the AccessibleContext associated with this JComponent

Returns:

the AccessibleContext of this JComponent

Overrides:

getAccessibleContext in class JComponent

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