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Chapter 19 java.awt Reference |
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Scrollbar
Name
Scrollbar
![[Graphic: Figure from the text]](./figs/scroll3.gif)
Description
The Scrollbar is a Component that provides the means to get and set values within a predetermined range. For example, a scrollbar could be used for a volume control. Scrollbars are most frequently used to help users manipulate areas too large to be displayed on the screen (pre version 1.1) or to set a value within an integer range.
Class Definition
public class java.awt.Scrollbar
extends java.awt.Component
implements java.awt.Adjustable {
// Constants
public final static int HORIZONTAL;
public final static int VERTICAL;
// Constructors
public Scrollbar();
public Scrollbar (int orientation);
public Scrollbar (int orientation, int value, int visible, int minimum,
int maximum);
// Instance Methods
public void addAdjustmentListener (AdjustmentListener l); 
public void addNotify();
public int getBlockIncrement();
public int getLineIncrement(); 
public int getMaximum();
public int getMinimum();
public int getOrientation();
public int getPageIncrement();
public int getUnitIncrement();
public int getValue();
public int getVisible();
public int getVisibleAmount();
public void removeAdjustmentListener (AdjustmentListener l);
public synchronized void setBlockIncrement (int v);
public void setLineIncrement (int amount);
public synchronized void setMaximum (int newMaximum);
public synchronized void setMinimum (int newMinimum);
public synchronized void setOrientation (int orientation);
public void setPageIncrement (int amount);
public synchronized void setUnitIncrement(int v);
public synchronized void setValue (int value);
public synchronized void setValues (int value, int visible,
int minimum, int maximum);
public synchronized void setVisibleAmount (int newAmount);
// Protected Instance Methods
protected String paramString();
protected void processAdjustmentEvent (AdjustmentEvent e);
protected void processEvent (AWTEvent e);
}
Constants
HORIZONTAL
public final static int HORIZONTAL
Constant used for a Scrollbar with a horizontal orientation.
VERTICAL
public final static int VERTICAL
Constant used for a Scrollbar with a vertical orientation.
Constructors
Scrollbar
public Scrollbar()
- Description
-
Constructs a vertical Scrollbar object; slider size, minimum value, maximum value, and initial value are all zero.
public Scrollbar (int orientation)
- Parameters
-
- orientation
-
Scrollbar constant designating direction.
- orientation
- Throws
-
- IllegalArgumentException
-
If orientation is invalid.
- IllegalArgumentException
- Description
-
Constructs a Scrollbar object, in the designated direction; slider size, minimum value, maximum value, and initial value are all zero.
public Scrollbar (int orientation, int value, int visible, int minimum, int maximum)
- Parameters
-
- orientation
-
Scrollbar constant designating direction.
- value
-
Initial value of Scrollbar.
- visible
-
Initial slider size.
- minimum
-
Initial minimum value.
- maximum
-
Initial maximum value.
- orientation
- Throws
-
- IllegalArgumentException
-
If orientation is invalid.
- IllegalArgumentException
- Description
-
Constructs a Scrollbar object with the given values.
Instance Methods
addAdjustmentListener
public void addAdjustmentListener (AdjustmentListener l)
- Parameters
-
- l
-
An object that implements the AdjustmentListener interface.
- l
- Implements
-
Adjustable.addAdjustmentListener()
- Description
-
Add a listener for adjustment event.
addNotify
public void addNotify()
- Overrides
-
Component.addNotify()
- Description
-
Creates Scrollbar's peer.
getBlockIncrement
public int getBlockIncrement()
- Implements
-
Adjustable.getBlockIncrement()
- Returns
-
The amount to scroll when a paging area is selected.
getLineIncrement
public int getLineIncrement()
- Returns
-
The amount to scroll when one of the arrows at the ends of the scrollbar is selected. Replaced by getUnitIncrement().
getMaximum
public int getMaximum()
- Implements
-
Adjustable.getMaximum()
- Returns
-
The maximum value that the Scrollbar can take.
getMinimum
public int getMinimum()
- Implements
-
Adjustable.getMinimum()
- Returns
-
The minimum value that the Scrollbar can take.
getOrientation
public int getOrientation()
- Implements
-
Adjustable.getOrientation()
- Returns
-
A constant representing the direction of the Scrollbar.
getPageIncrement
public int getPageIncrement()
- Returns
-
The amount to scroll when a paging area is selected. Replaced with getBlockIncrement().
getUnitIncrement
public int getUnitIncrement()
- Implements
-
Adjustable.getUnitIncrement()
- Returns
-
The amount to scroll when one of the arrows at the ends of the scrollbar is selected.
getValue
public int getValue()
- Implements
-
Adjustable.getValue()
- Returns
-
The current setting for the Scrollbar.
getVisible
public int getVisible()
- Returns
-
The current visible setting (i.e., size) for the slider. Replaced by getVisibleAmount().
getVisibleAmount
public int getVisibleAmount()
- Implements
-
Adjustable.getVisibleAmount()
- Returns
-
The current visible setting (i.e., size) for the slider.
removeAdjustmentListener
public void removeAdjustmentListener (AdjustmentListener l)
- Parameters
-
- l
-
One of this Scrollbar's AdjustmentListeners.
- l
- Implements
-
Adjustable.removeAdjustmentListener()
- Description
-
Remove an adjustment event listener.
setBlockIncrement
public synchronized void setBlockIncrement (int amount)
- Parameters
-
- amount
-
New paging increment amount.
- amount
- Implements
-
Adjustable.setBlockIncrement()
- Description
-
Changes the block increment amount for the Scrollbar; the default block increment is 10.
setLineIncrement
public void setLineIncrement (int amount)
- Parameters
-
- amount
-
New line increment amount.
- amount
- Description
-
Changes the line increment amount for the Scrollbar. The default line increment is 1. Replaced by setUnitIncrement(int).
setMaximum
public synchronized void setMaximum (int newMaximum)
- Parameters
-
- newMaximum
-
New maximum value.
- newMaximum
- Implements
-
Adjustable.setMaximum()
- Description
-
Changes the maximum value for the Scrollbar.
setMinimum
public synchronized void setMinimum (int newMinimum)
- Parameters
-
- newMinimum
-
New minimum value.
- newMinimum
- Implements
-
Adjustable.setMinimum()
- Description
-
Changes the minimum value for the Scrollbar.
setOrientation
public synchronized void setOrientation (int orientation)
- Parameters
-
- orientation
-
One of the orientation constants HORIZONTAL or VERTICAL.
- orientation
- Description
-
Changes the orientation of the Scrollbar.
setPageIncrement
public void setPageIncrement (int amount)
- Parameters
-
- amount
-
New paging increment amount.
- amount
- Description
-
Changes the paging increment amount for the Scrollbar; the default page increment is 10. Replaced by setBlockIncrement(int).
setUnitIncrement
public synchronized void setUnitIncrement (int amount)
- Parameters
-
- amount
-
New line increment amount.
- amount
- Implements
-
Adjustable.setUnitIncrement()
- Description
-
Changes the unit increment amount for the Scrollbar. The default unit increment is 1.
setValue
public synchronized void setValue (int value)
- Parameters
-
- value
-
New Scrollbar value.
- value
- Implements
-
Adjustable.setValue()
- Description
-
Changes the current value of the Scrollbar.
setValues
public synchronized void setValues (int value, int visible, int minimum, int maximum)
- Parameters
-
- value
-
New Scrollbar value.
- visible
-
New slider width.
- minimum
-
New minimum value for Scrollbar.
- maximum
-
New maximum value for Scrollbar.
- value
- Description
-
Changes the settings of the Scrollbar to the given amounts.
setVisibleAmount
public synchronized void setVisibleAmount (int newAmount)
- Parameters
-
- newAmount
-
New amount visible.
- newAmount
- Implements
-
Adjustable.setVisibleAmount()
- Description
-
Changes the current visible amount of the Scrollbar.
Protected Instance Methods
paramString
protected String paramString()
- Returns
-
String with current settings of Scrollbar.
- Overrides
-
Component.paramString()
- Description
-
Helper method for toString() to generate string of current settings.
processAdjustmentEvent
protected void processAdjustmentEvent (AdjustmentEvent e)
- Parameters
-
- e
-
The adjustment event to process.
- e
- Description
-
Adjustment events are passed to this method for processing. Normally, this method is called by processEvent().
processEvent
protected void processEvent (AWTEvent e)
- Parameters
-
- e
-
The event to process.
- e
- Description
-
Low level AWTEvents are passed to this method for processing.
See Also
Adjustable, Component, String
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| ScrollPane |
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Shape |
