Scrollbar

Name

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.
• Throws
• • IllegalArgumentException
  • If orientation is invalid.
• 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.
• Throws
• • IllegalArgumentException
  • If orientation is invalid.
• 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.
• 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.
• Implements
• Adjustable.removeAdjustmentListener()
• Description
• Remove an adjustment event listener.

setBlockIncrement

public synchronized void setBlockIncrement (int amount)

• Parameters
• • amount
  • New paging increment 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.
• 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.
• Implements
• Adjustable.setMaximum()
• Description
• Changes the maximum value for the Scrollbar.

setMinimum

public synchronized void setMinimum (int newMinimum)

• Parameters
• • newMinimum
  • New minimum value.
• 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.
• Description
• Changes the orientation of the Scrollbar.

setPageIncrement

public void setPageIncrement (int amount)

• Parameters
• • amount
  • New paging increment 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.
• 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.
• 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.
• Description
• Changes the settings of the Scrollbar to the given amounts.

setVisibleAmount

public synchronized void setVisibleAmount (int newAmount)

• Parameters
• • newAmount
  • New amount visible.
• 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.
• 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.
• Description
• Low level AWTEvents are passed to this method for processing.

See Also

Adjustable, Component, String