File	Doc	Category	Size	Date	Package
JScrollBar.java	API Doc	Java SE 6 API	27920	Tue Jun 10 00:26:38 BST 2008	javax.swing

JScrollBar

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

Fields Summary
private static final String	uiClassID
private ChangeListener	fwdAdjustmentEvents All changes from the model are treated as though the user moved the scrollbar knob.
protected BoundedRangeModel	model The model that represents the scrollbar's minimum, maximum, extent (aka "visibleAmount") and current value.
protected int	orientation
protected int	unitIncrement
protected int	blockIncrement

Constructors Summary
public JScrollBar(int orientation, int value, int extent, int min, int max) Creates a scrollbar with the specified orientation, value, extent, minimum, 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. exception IllegalArgumentException if orientation is not one of VERTICAL, HORIZONTAL see #setOrientation see #setValue see #setVisibleAmount see #setMinimum see #setMaximum checkOrientation(orientation); this.unitIncrement = 1; this.blockIncrement = (extent == 0) ? 1 : extent; this.orientation = orientation; this.model = new DefaultBoundedRangeModel(value, extent, min, max); this.model.addChangeListener(fwdAdjustmentEvents); setRequestFocusEnabled(false); updateUI();
public JScrollBar(int orientation) Creates a scrollbar with the specified orientation and the following initial values: minimum = 0 maximum = 100 value = 0 extent = 10 this(orientation, 0, 10, 0, 100);
public JScrollBar() Creates a vertical scrollbar with the following initial values: minimum = 0 maximum = 100 value = 0 extent = 10 this(VERTICAL);

Methods Summary
public void	addAdjustmentListener(java.awt.event.AdjustmentListener l) Adds an AdjustmentListener. Adjustment listeners are notified each time the scrollbar's model changes. Adjustment events are provided for backwards compatibility 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. param l the AdjustmentLister to add see #removeAdjustmentListener see BoundedRangeModel#addChangeListener listenerList.add(AdjustmentListener.class, l);
private void	checkOrientation(int orientation) switch (orientation) { case VERTICAL: case HORIZONTAL: break; default: throw new IllegalArgumentException("orientation must be one of: VERTICAL, HORIZONTAL"); }
protected void	fireAdjustmentValueChanged(int id, int type, int value) Notify listeners that the scrollbar's model has changed. see #addAdjustmentListener see EventListenerList fireAdjustmentValueChanged(id, type, value, getValueIsAdjusting());
private void	fireAdjustmentValueChanged(int id, int type, int value, boolean isAdjusting) Notify listeners that the scrollbar's model has changed. see #addAdjustmentListener see EventListenerList Object[] listeners = listenerList.getListenerList(); AdjustmentEvent e = null; for (int i = listeners.length - 2; i >= 0; i -= 2) { if (listeners[i]==AdjustmentListener.class) { if (e == null) { e = new AdjustmentEvent(this, id, type, value, isAdjusting); } ((AdjustmentListener)listeners[i+1]).adjustmentValueChanged(e); } }
public javax.accessibility.AccessibleContext	getAccessibleContext() Gets the AccessibleContext associated with this JScrollBar. For JScrollBar, the AccessibleContext takes the form of an AccessibleJScrollBar. A new AccessibleJScrollBar instance is created if necessary. return an AccessibleJScrollBar that serves as the AccessibleContext of this JScrollBar if (accessibleContext == null) { accessibleContext = new AccessibleJScrollBar(); } return accessibleContext;
public java.awt.event.AdjustmentListener[]	getAdjustmentListeners() Returns an array of all the AdjustmentListeners added to this JScrollBar with addAdjustmentListener(). return all of the AdjustmentListeners added or an empty array if no listeners have been added since 1.4 return (AdjustmentListener[])listenerList.getListeners( AdjustmentListener.class);
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. param direction is -1 or 1 for up/down respectively return the value of the blockIncrement property see #setBlockIncrement see #setValue see Scrollable#getScrollableBlockIncrement return blockIncrement;
public int	getBlockIncrement() For backwards compatibility with java.awt.Scrollbar. see Adjustable#getBlockIncrement see #getBlockIncrement(int) return blockIncrement;
public int	getMaximum() The maximum value of the scrollbar is maximum - extent. return the value of the model's maximum property see #setMaximum return getModel().getMaximum();
public java.awt.Dimension	getMaximumSize() The scrollbar is flexible along it's scrolling axis and rigid along the other axis. Dimension pref = getPreferredSize(); if (getOrientation() == VERTICAL) { return new Dimension(pref.width, Short.MAX_VALUE); } else { return new Dimension(Short.MAX_VALUE, pref.height); }
public int	getMinimum() Returns the minimum value supported by the scrollbar (usually zero). return the value of the model's minimum property see #setMinimum return getModel().getMinimum();
public java.awt.Dimension	getMinimumSize() The scrollbar is flexible along it's scrolling axis and rigid along the other axis. Dimension pref = getPreferredSize(); if (orientation == VERTICAL) { return new Dimension(pref.width, 5); } else { return new Dimension(5, pref.height); }
public javax.swing.BoundedRangeModel	getModel() Returns data model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent. see #setModel return model;
public int	getOrientation() Returns the component's orientation (horizontal or vertical). return VERTICAL or HORIZONTAL see #setOrientation see java.awt.Adjustable#getOrientation return orientation;
public javax.swing.plaf.ScrollBarUI	getUI() Returns the delegate that implements the look and feel for this component. see JComponent#setUI return (ScrollBarUI)ui;
public java.lang.String	getUIClassID() Returns the name of the LookAndFeel class for this component. return "ScrollBarUI" see JComponent#getUIClassID see UIDefaults#getUI return uiClassID;
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. param direction is -1 or 1 for up/down respectively return the value of the unitIncrement property see #setUnitIncrement see #setValue see Scrollable#getScrollableUnitIncrement return unitIncrement;
public int	getUnitIncrement() For backwards compatibility with java.awt.Scrollbar. see Adjustable#getUnitIncrement see #getUnitIncrement(int) return unitIncrement;
public int	getValue() Returns the scrollbar's value. return the model's value property see #setValue return getModel().getValue();
public boolean	getValueIsAdjusting() True if the scrollbar knob is being dragged. return the value of the model's valueIsAdjusting property see #setValueIsAdjusting return getModel().getValueIsAdjusting();
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. return the value of the model's extent property see #setVisibleAmount return getModel().getExtent();
protected java.lang.String	paramString() Returns a string representation of this JScrollBar. This method is intended to be used only for debugging purposes, and the content and format of the returned string may vary between implementations. The returned string may be empty but may not be null. return a string representation of this JScrollBar. String orientationString = (orientation == HORIZONTAL ? "HORIZONTAL" : "VERTICAL"); return super.paramString() + ",blockIncrement=" + blockIncrement + ",orientation=" + orientationString + ",unitIncrement=" + unitIncrement;
public void	removeAdjustmentListener(java.awt.event.AdjustmentListener l) Removes an AdjustmentEvent listener. param l the AdjustmentLister to remove see #addAdjustmentListener listenerList.remove(AdjustmentListener.class, l);
public void	setBlockIncrement(int blockIncrement) Sets the blockIncrement property. Note, that if the argument is equal to the value of Integer.MIN_VALUE, the most look and feels will not provide the scrolling to the right/down. see #getBlockIncrement() beaninfo preferred: true bound: true description: The scrollbar's block increment. int oldValue = this.blockIncrement; this.blockIncrement = blockIncrement; firePropertyChange("blockIncrement", oldValue, blockIncrement);
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. param x a boolean value, where true enables the component and false disables it super.setEnabled(x); Component[] children = getComponents(); for(int i = 0; i < children.length; i++) { children[i].setEnabled(x); }
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 #getMaximum see BoundedRangeModel#setMaximum beaninfo preferred: true description: The scrollbar's maximum value. getModel().setMaximum(maximum);
public void	setMinimum(int minimum) Sets the model's minimum property. see #getMinimum see BoundedRangeModel#setMinimum beaninfo preferred: true description: The scrollbar's minimum value. getModel().setMinimum(minimum);
public void	setModel(javax.swing.BoundedRangeModel newModel) Sets the model that handles the scrollbar's four fundamental properties: minimum, maximum, value, extent. see #getModel beaninfo bound: true expert: true description: The scrollbar's BoundedRangeModel. Integer oldValue = null; BoundedRangeModel oldModel = model; if (model != null) { model.removeChangeListener(fwdAdjustmentEvents); oldValue = new Integer(model.getValue()); } model = newModel; if (model != null) { model.addChangeListener(fwdAdjustmentEvents); } firePropertyChange("model", oldModel, model); if (accessibleContext != null) { accessibleContext.firePropertyChange( AccessibleContext.ACCESSIBLE_VALUE_PROPERTY, oldValue, new Integer(model.getValue())); }
public void	setOrientation(int orientation) Set the scrollbar's orientation to either VERTICAL or HORIZONTAL. exception IllegalArgumentException if orientation is not one of VERTICAL, HORIZONTAL see #getOrientation beaninfo preferred: true bound: true attribute: visualUpdate true description: The scrollbar's orientation. enum: VERTICAL JScrollBar.VERTICAL HORIZONTAL JScrollBar.HORIZONTAL checkOrientation(orientation); int oldValue = this.orientation; this.orientation = orientation; firePropertyChange("orientation", oldValue, orientation); if ((oldValue != orientation) && (accessibleContext != null)) { accessibleContext.firePropertyChange( AccessibleContext.ACCESSIBLE_STATE_PROPERTY, ((oldValue == VERTICAL) ? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL), ((orientation == VERTICAL) ? AccessibleState.VERTICAL : AccessibleState.HORIZONTAL)); } if (orientation != oldValue) { revalidate(); }
public void	setUI(javax.swing.plaf.ScrollBarUI ui) Sets the L&F object that renders this component. param ui the ScrollBarUI L&F object see UIDefaults#getUI since 1.4 beaninfo bound: true hidden: true attribute: visualUpdate true description: The UI object that implements the Component's LookAndFeel super.setUI(ui);
public void	setUnitIncrement(int unitIncrement) Sets the unitIncrement property. Note, that if the argument is equal to the value of Integer.MIN_VALUE, the most look and feels will not provide the scrolling to the right/down. see #getUnitIncrement beaninfo preferred: true bound: true description: The scrollbar's unit increment. int oldValue = this.unitIncrement; this.unitIncrement = unitIncrement; firePropertyChange("unitIncrement", oldValue, unitIncrement);
public void	setValue(int value) Sets the scrollbar's value. This method just forwards the value to the model. see #getValue see BoundedRangeModel#setValue beaninfo preferred: true description: The scrollbar's current value. BoundedRangeModel m = getModel(); int oldValue = m.getValue(); m.setValue(value); if (accessibleContext != null) { accessibleContext.firePropertyChange( AccessibleContext.ACCESSIBLE_VALUE_PROPERTY, new Integer(oldValue), new Integer(m.getValue())); }
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 #getValueIsAdjusting see BoundedRangeModel#setValueIsAdjusting beaninfo expert: true description: True if the scrollbar thumb is being dragged. BoundedRangeModel m = getModel(); boolean oldValue = m.getValueIsAdjusting(); m.setValueIsAdjusting(b); if ((oldValue != b) && (accessibleContext != null)) { accessibleContext.firePropertyChange( AccessibleContext.ACCESSIBLE_STATE_PROPERTY, ((oldValue) ? AccessibleState.BUSY : null), ((b) ? AccessibleState.BUSY : null)); }
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 BoundedRangeModel#setRangeProperties see #setValue see #setVisibleAmount see #setMinimum see #setMaximum BoundedRangeModel m = getModel(); int oldValue = m.getValue(); m.setRangeProperties(newValue, newExtent, newMin, newMax, m.getValueIsAdjusting()); if (accessibleContext != null) { accessibleContext.firePropertyChange( AccessibleContext.ACCESSIBLE_VALUE_PROPERTY, new Integer(oldValue), new Integer(m.getValue())); }
public void	setVisibleAmount(int extent) Set the model's extent property. see #getVisibleAmount see BoundedRangeModel#setExtent beaninfo preferred: true description: The amount of the view that is currently visible. getModel().setExtent(extent);
public void	updateUI() Overrides JComponent.updateUI. see JComponent#updateUI setUI((ScrollBarUI)UIManager.getUI(this));
private void	writeObject(java.io.ObjectOutputStream s) See readObject() and writeObject() in JComponent for more information about serialization in Swing. s.defaultWriteObject(); if (getUIClassID().equals(uiClassID)) { byte count = JComponent.getWriteObjCounter(this); JComponent.setWriteObjCounter(this, --count); if (count == 0 && ui != null) { ui.installUI(this); } }