# Class JScrollPane.ScrollBar

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

All Implemented Interfaces:
  `Adjustable`, `ImageObserver`, `MenuContainer`, `Serializable`, `Accessible`, `UIResource`

Enclosing class:
  `JScrollPane`

protected class JScrollPane.ScrollBar extends JScrollBar implements UIResource
By default `JScrollPane` creates scrollbars that are instances of this class. `Scrollbar` overrides the `getUnitIncrement` and `getBlockIncrement` methods so that, if the viewport's view is a `Scrollable`, the view is asked to compute these values. Unless the unit/block increment have been explicitly set.

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 has been added to the `java.beans` package. Please see `XMLEncoder`.

Since:
  1.2
See Also:
  - `Scrollable`
  - `JScrollPane.createVerticalScrollBar()`
  - `JScrollPane.createHorizontalScrollBar()`

- ## Nested Class Summary

  ### Nested classes/interfaces declared in class javax.swing.JScrollBar

  `JScrollBar.AccessibleJScrollBar`

  ### Nested classes/interfaces declared in class javax.swing.JComponent

  `JComponent.AccessibleJComponent`

  ### Nested classes/interfaces declared in class java.awt.Container

  `Container.AccessibleAWTContainer`

  ### Nested classes/interfaces declared in class java.awt.Component

  `Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy`

- ## Field Summary

  ### Fields declared in class javax.swing.JScrollBar

  `blockIncrement, model, orientation, unitIncrement`

  ### Fields declared in class javax.swing.JComponent

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

  ### Fields declared in class java.awt.Component

  `accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT`

  ### Fields declared in interface java.awt.Adjustable

  `HORIZONTAL, NO_ORIENTATION, VERTICAL`

  ### Fields declared in interface java.awt.image.ImageObserver

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

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `ScrollBar(int orientation)`
  Creates a scrollbar with the specified orientation.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `int`
  `getBlockIncrement(int direction)`
  Computes the block increment for scrolling if the viewport's view is a `Scrollable` object.
  `int`
  `getUnitIncrement(int direction)`
  Computes the unit increment for scrolling if the viewport's view is a `Scrollable` object.
  `void`
  `setBlockIncrement(int blockIncrement)`
  Messages super to set the value, and resets the `blockIncrementSet` instance variable to true.
  `void`
  `setUnitIncrement(int unitIncrement)`
  Messages super to set the value, and resets the `unitIncrementSet` instance variable to true.

  ### Methods declared in class javax.swing.JScrollBar

  `addAdjustmentListener, fireAdjustmentValueChanged, getAccessibleContext, getAdjustmentListeners, getBlockIncrement, getMaximum, getMaximumSize, getMinimum, getMinimumSize, getModel, getOrientation, getUI, getUIClassID, getUnitIncrement, getValue, getValueIsAdjusting, getVisibleAmount, paramString, removeAdjustmentListener, setEnabled, setMaximum, setMaximumSize, setMinimum, setMinimumSize, setModel, setOrientation, setUI, setValue, setValueIsAdjusting, setValues, setVisibleAmount, updateUI`

  ### Methods declared in class javax.swing.JComponent

  `addAncestorListener, addNotify, addVetoableChangeListener, computeVisibleRect, contains, createToolTip, disable, enable, firePropertyChange, firePropertyChange, fireVetoableChange, getActionForKeyStroke, getActionMap, getAlignmentX, getAlignmentY, getAncestorListeners, getAutoscrolls, getBaseline, getBaselineResizeBehavior, getBorder, getBounds, getClientProperty, getComponentGraphics, getComponentPopupMenu, getConditionForKeyStroke, getDebugGraphicsOptions, getDefaultLocale, getFontMetrics, getGraphics, getHeight, getInheritsPopupMenu, getInputMap, getInputMap, getInputVerifier, getInsets, getInsets, getListeners, getLocation, getNextFocusableComponent, getPopupLocation, getPreferredSize, getRegisteredKeyStrokes, getRootPane, getSize, getToolTipLocation, getToolTipText, getToolTipText, getTopLevelAncestor, getTransferHandler, getVerifyInputWhenFocusTarget, getVetoableChangeListeners, getVisibleRect, getWidth, getX, getY, grabFocus, hide, isDoubleBuffered, isLightweightComponent, isManagingFocus, isOpaque, isOptimizedDrawingEnabled, isPaintingForPrint, isPaintingOrigin, isPaintingTile, isRequestFocusEnabled, isValidateRoot, paint, paintBorder, paintChildren, paintComponent, paintImmediately, paintImmediately, print, printAll, printBorder, printChildren, printComponent, processComponentKeyEvent, processKeyBinding, processKeyEvent, processMouseEvent, processMouseMotionEvent, putClientProperty, registerKeyboardAction, registerKeyboardAction, removeAncestorListener, removeNotify, removeVetoableChangeListener, repaint, repaint, requestDefaultFocus, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, resetKeyboardActions, reshape, revalidate, scrollRectToVisible, setActionMap, setAlignmentX, setAlignmentY, setAutoscrolls, setBackground, setBorder, setComponentPopupMenu, setDebugGraphicsOptions, setDefaultLocale, setDoubleBuffered, setFocusTraversalKeys, setFont, setForeground, setInheritsPopupMenu, setInputMap, setInputVerifier, setNextFocusableComponent, setOpaque, setPreferredSize, setRequestFocusEnabled, setToolTipText, setTransferHandler, setUI, setVerifyInputWhenFocusTarget, setVisible, unregisterKeyboardAction, update`

  ### Methods declared in class java.awt.Container

  `add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getComponentZOrder, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getLayout, getMousePosition, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicyProvider, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paintComponents, preferredSize, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, setComponentZOrder, setFocusCycleRoot, setFocusTraversalPolicy, setFocusTraversalPolicyProvider, setLayout, transferFocusDownCycle, validate, validateTree`

  ### Methods declared in class java.awt.Component

  `action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, createImage, createImage, createVolatileImage, createVolatileImage, disableEvents, dispatchEvent, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getForeground, getGraphicsConfiguration, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getToolkit, getTreeLock, gotFocus, handleEvent, hasFocus, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, resize, resize, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setFocusable, setFocusTraversalKeysEnabled, setIgnoreRepaint, setLocale, setLocation, setLocation, setMixingCutoutShape, setName, setSize, setSize, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle`

  ### Methods declared in class java.lang.Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- ## Constructor Details

  - ### ScrollBar

    public ScrollBar(int orientation)
    Creates a scrollbar with the specified orientation. The options are:
    - `ScrollPaneConstants.VERTICAL`
    - `ScrollPaneConstants.HORIZONTAL`
    Parameters:
      `orientation` - an integer specifying one of the legal orientation values shown above
    Since:
      1.4

- ## Method Details

  - ### setUnitIncrement

    public void setUnitIncrement(int unitIncrement)
    Messages super to set the value, and resets the `unitIncrementSet` instance variable to true.
    Specified by:
      `setUnitIncrement` in interface `Adjustable`
    Overrides:
      `setUnitIncrement` in class `JScrollBar`
    Parameters:
      `unitIncrement` - the new unit increment value, in pixels
    See Also:
      - `JScrollBar.getUnitIncrement(int)`

  - ### getUnitIncrement

    public int getUnitIncrement(int direction)
    Computes the unit increment for scrolling if the viewport's view is a `Scrollable` object. Otherwise return `super.getUnitIncrement`.
    Overrides:
      `getUnitIncrement` in class `JScrollBar`
    Parameters:
      `direction` - less than zero to scroll up/left, greater than zero for down/right
    Returns:
      an integer, in pixels, containing the unit increment
    See Also:
      - `Scrollable.getScrollableUnitIncrement(java.awt.Rectangle, int, int)`

  - ### setBlockIncrement

    public void setBlockIncrement(int blockIncrement)
    Messages super to set the value, and resets the `blockIncrementSet` instance variable to true.
    Specified by:
      `setBlockIncrement` in interface `Adjustable`
    Overrides:
      `setBlockIncrement` in class `JScrollBar`
    Parameters:
      `blockIncrement` - the new block increment value, in pixels
    See Also:
      - `JScrollBar.getBlockIncrement()`

  - ### getBlockIncrement

    public int getBlockIncrement(int direction)
    Computes the block increment for scrolling if the viewport's view is a `Scrollable` object. Otherwise the `blockIncrement` equals the viewport's width or height. If there's no viewport return `super.getBlockIncrement`.
    Overrides:
      `getBlockIncrement` in class `JScrollBar`
    Parameters:
      `direction` - less than zero to scroll up/left, greater than zero for down/right
    Returns:
      an integer, in pixels, containing the block increment
    See Also:
      - `Scrollable.getScrollableBlockIncrement(java.awt.Rectangle, int, int)`