SynthScrollBarUI (Java Platform SE 8 )
Keywords: javax.swing.plaf.synth.SynthScrollBarUI class
Date: 2026-04-22

javax.swing.plaf.synth

## Class SynthScrollBarUI

- java.lang.Object
- - javax.swing.plaf.ComponentUI
  - - javax.swing.plaf.ScrollBarUI
    - - javax.swing.plaf.basic.BasicScrollBarUI
      - - javax.swing.plaf.synth.SynthScrollBarUI

- All Implemented Interfaces:
    LayoutManager, PropertyChangeListener, EventListener, SynthConstants, SynthUI, SwingConstants

      public class SynthScrollBarUI
      extends BasicScrollBarUI
      implements PropertyChangeListener, SynthUI

  Provides the Synth L&F UI delegate for `JScrollBar`.
  Since:
    1.7

- - ### Nested Class Summary

    - ### Nested classes/interfaces inherited from class javax.swing.plaf.basic.BasicScrollBarUI

      `BasicScrollBarUI.ArrowButtonListener, BasicScrollBarUI.ModelListener, BasicScrollBarUI.PropertyChangeHandler, BasicScrollBarUI.ScrollListener, BasicScrollBarUI.TrackListener`

  - ### Field Summary

    - ### Fields inherited from class javax.swing.plaf.basic.BasicScrollBarUI

      `buttonListener, decrButton, DECREASE_HIGHLIGHT, decrGap, incrButton, INCREASE_HIGHLIGHT, incrGap, isDragging, maximumThumbSize, minimumThumbSize, modelListener, NO_HIGHLIGHT, propertyChangeListener, scrollbar, scrollBarWidth, scrollListener, scrollTimer, thumbColor, thumbDarkShadowColor, thumbHighlightColor, thumbLightShadowColor, thumbRect, trackColor, trackHighlight, trackHighlightColor, trackListener, trackRect`

    - ### Fields inherited from interface javax.swing.plaf.synth.SynthConstants

      `DEFAULT, DISABLED, ENABLED, FOCUSED, MOUSE_OVER, PRESSED, SELECTED`

    - ### Fields inherited from interface javax.swing.SwingConstants

      `BOTTOM, CENTER, EAST, HORIZONTAL, LEADING, LEFT, NEXT, NORTH, NORTH_EAST, NORTH_WEST, PREVIOUS, RIGHT, SOUTH, SOUTH_EAST, SOUTH_WEST, TOP, TRAILING, VERTICAL, WEST`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `SynthScrollBarUI()`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `protected void` | `configureScrollBarColors()`
    `protected JButton` | `createDecreaseButton(int orientation)`
    `protected JButton` | `createIncreaseButton(int orientation)`
    `static ComponentUI` | `createUI(JComponent c)`
    `SynthContext` | `getContext(JComponent c)` Returns the Context for the specified component.
    `protected Dimension` | `getMinimumThumbSize()` Returns the smallest acceptable size for the thumb.
    `Dimension` | `getPreferredSize(JComponent c)` A vertical scrollbar's preferred width is the maximum of preferred widths of the (non `null`) increment/decrement buttons, and the minimum width of the thumb.
    `boolean` | `getSupportsAbsolutePositioning()` Indicates whether the user can absolutely position the thumb with a mouse gesture (usually the middle mouse button).
    `protected void` | `installDefaults()`
    `protected void` | `installListeners()`
    `void` | `paint(Graphics g, JComponent c)` Paints the specified component according to the Look and Feel.
    `protected void` | `paint(SynthContext context, Graphics g)` Paints the specified component.
    `void` | `paintBorder(SynthContext context, Graphics g, int x, int y, int w, int h)` Paints the border.
    `protected void` | `paintThumb(SynthContext context, Graphics g, Rectangle thumbBounds)` Paints the scrollbar thumb.
    `protected void` | `paintTrack(SynthContext context, Graphics g, Rectangle trackBounds)` Paints the scrollbar track.
    `void` | `propertyChange(PropertyChangeEvent e)` This method gets called when a bound property is changed.
    `protected void` | `setThumbRollover(boolean active)` Sets whether or not the mouse is currently over the thumb.
    `protected void` | `uninstallDefaults()`
    `protected void` | `uninstallListeners()`
    `void` | `update(Graphics g, JComponent c)` Notifies this UI delegate to repaint the specified component.

    - ### Methods inherited from class javax.swing.plaf.basic.BasicScrollBarUI

      `addLayoutComponent, createArrowButtonListener, createModelListener, createPropertyChangeListener, createScrollListener, createTrackListener, getMaximumSize, getMaximumThumbSize, getThumbBounds, getTrackBounds, installComponents, installKeyboardActions, installUI, isThumbRollover, layoutContainer, layoutHScrollbar, layoutVScrollbar, minimumLayoutSize, paintDecreaseHighlight, paintIncreaseHighlight, paintThumb, paintTrack, preferredLayoutSize, removeLayoutComponent, scrollByBlock, scrollByUnit, setThumbBounds, uninstallComponents, uninstallKeyboardActions, uninstallUI`

    - ### Methods inherited from class javax.swing.plaf.ComponentUI

      `contains, getAccessibleChild, getAccessibleChildrenCount, getBaseline, getBaselineResizeBehavior, getMinimumSize`

    - ### Methods inherited from class java.lang.Object

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

- - ### Constructor Detail

    - #### SynthScrollBarUI

          public SynthScrollBarUI()

  - ### Method Detail

    - #### createUI

          public static ComponentUI createUI(JComponent c)

    - #### installDefaults

          protected void installDefaults()

      Overrides:
        `installDefaults` in class `BasicScrollBarUI`

    - #### configureScrollBarColors

          protected void configureScrollBarColors()

      Overrides:
        `configureScrollBarColors` in class `BasicScrollBarUI`

    - #### installListeners

          protected void installListeners()

      Overrides:
        `installListeners` in class `BasicScrollBarUI`

    - #### uninstallListeners

          protected void uninstallListeners()

      Overrides:
        `uninstallListeners` in class `BasicScrollBarUI`

    - #### uninstallDefaults

          protected void uninstallDefaults()

      Overrides:
        `uninstallDefaults` in class `BasicScrollBarUI`

    - #### getContext

          public SynthContext getContext(JComponent c)

      Returns the Context for the specified component.
      Specified by:
        `getContext` in interface `SynthUI`
      Parameters:
        `c` - Component requesting SynthContext.
      Returns:
        SynthContext describing component.

    - #### getSupportsAbsolutePositioning

          public boolean getSupportsAbsolutePositioning()

      Indicates whether the user can absolutely position the thumb with a mouse gesture (usually the middle mouse button).
      Overrides:
        `getSupportsAbsolutePositioning` in class `BasicScrollBarUI`
      Returns:
        true if a mouse gesture can absolutely position the thumb

    - #### update

          public void update(Graphics g,
                             JComponent c)

      Notifies this UI delegate to repaint the specified component. This method paints the component background, then calls the `paint(SynthContext,Graphics)` method.

      In general, this method does not need to be overridden by subclasses. All Look and Feel rendering code should reside in the `paint` method.

      Overrides:
        `update` in class `ComponentUI`
      Parameters:
        `g` - the `Graphics` object used for painting
        `c` - the component being painted
      See Also:
        `paint(SynthContext,Graphics)`

    - #### paint

          public void paint(Graphics g,
                            JComponent c)

      Paints the specified component according to the Look and Feel.

      This method is not used by Synth Look and Feel. Painting is handled by the `paint(SynthContext,Graphics)` method.

      Overrides:
        `paint` in class `BasicScrollBarUI`
      Parameters:
        `g` - the `Graphics` object used for painting
        `c` - the component being painted
      See Also:
        `paint(SynthContext,Graphics)`

    - #### paint

          protected void paint(SynthContext context,
                               Graphics g)

      Paints the specified component.
      Parameters:
        `context` - context for the component being painted
        `g` - the `Graphics` object used for painting
      See Also:
        `update(Graphics,JComponent)`

    - #### paintBorder

          public void paintBorder(SynthContext context,
                                  Graphics g,
                                  int x,
                                  int y,
                                  int w,
                                  int h)

      Paints the border.
      Specified by:
        `paintBorder` in interface `SynthUI`
      Parameters:
        `context` - a component context
        `g` - `Graphics` to paint on
        `x` - the X coordinate
        `y` - the Y coordinate
        `w` - width of the border
        `h` - height of the border

    - #### paintTrack

          protected void paintTrack(SynthContext context,
                                    Graphics g,
                                    Rectangle trackBounds)

      Paints the scrollbar track.
      Parameters:
        `context` - context for the component being painted
        `g` - `Graphics` object used for painting
        `trackBounds` - bounding box for the track

    - #### paintThumb

          protected void paintThumb(SynthContext context,
                                    Graphics g,
                                    Rectangle thumbBounds)

      Paints the scrollbar thumb.
      Parameters:
        `context` - context for the component being painted
        `g` - `Graphics` object used for painting
        `thumbBounds` - bounding box for the thumb

    - #### getPreferredSize

          public Dimension getPreferredSize(JComponent c)

      A vertical scrollbar's preferred width is the maximum of preferred widths of the (non `null`) increment/decrement buttons, and the minimum width of the thumb. The preferred height is the sum of the preferred heights of the same parts. The basis for the preferred size of a horizontal scrollbar is similar.

      The `preferredSize` is only computed once, subsequent calls to this method just return a cached size.

      Overrides:
        `getPreferredSize` in class `BasicScrollBarUI`
      Parameters:
        `c` - the `JScrollBar` that's delegating this method to us
      Returns:
        the preferred size of a Basic JScrollBar
      See Also:
        `BasicScrollBarUI.getMaximumSize(javax.swing.JComponent)`, `ComponentUI.getMinimumSize(javax.swing.JComponent)`

    - #### getMinimumThumbSize

          protected Dimension getMinimumThumbSize()

      Returns the smallest acceptable size for the thumb. If the scrollbar becomes so small that this size isn't available, the thumb will be hidden.

      Warning : the value returned by this method should not be be modified, it's a shared static constant.

      Overrides:
        `getMinimumThumbSize` in class `BasicScrollBarUI`
      Returns:
        The smallest acceptable size for the thumb.
      See Also:
        `BasicScrollBarUI.getMaximumThumbSize()`

    - #### createDecreaseButton

          protected JButton createDecreaseButton(int orientation)

      Overrides:
        `createDecreaseButton` in class `BasicScrollBarUI`

    - #### createIncreaseButton

          protected JButton createIncreaseButton(int orientation)

      Overrides:
        `createIncreaseButton` in class `BasicScrollBarUI`

    - #### setThumbRollover

          protected void setThumbRollover(boolean active)

      Sets whether or not the mouse is currently over the thumb.
      Overrides:
        `setThumbRollover` in class `BasicScrollBarUI`
      Parameters:
        `active` - True indicates the thumb is currently active.

    - #### propertyChange

          public void propertyChange(PropertyChangeEvent e)

      Description copied from interface: `PropertyChangeListener`
      This method gets called when a bound property is changed.
      Specified by:
        `propertyChange` in interface `PropertyChangeListener`
      Parameters:
        `e` - A PropertyChangeEvent object describing the event source and the property that has changed.

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