BasicTreeUI.ComponentHandler (Java SE 14 & JDK 14)
Description: declaration: module: java.desktop, package: javax.swing.plaf.basic, class: BasicTreeUI, class: ComponentHandler
Keywords: javax.swing.plaf.basic.BasicTreeUI.ComponentHandler class

Module java.desktop
Package javax.swing.plaf.basic

# Class BasicTreeUI.ComponentHandler

java.lang.Object
java.awt.event.ComponentAdapter
javax.swing.plaf.basic.BasicTreeUI.ComponentHandler

All Implemented Interfaces:
  `ActionListener`, `ComponentListener`, `EventListener`

Enclosing class:
  BasicTreeUI

    public class BasicTreeUI.ComponentHandler
    extends ComponentAdapter
    implements ActionListener

Updates the preferred size when scrolling (if necessary).

- ## Field Summary

  Fields
  Modifier and Type | Field | Description
  --- | --- | ---
  `protected JScrollBar` | `scrollBar` | ScrollBar that is being adjusted.
  `protected Timer` | `timer` | Timer used when inside a scrollpane and the scrollbar is adjusting.

- ## Constructor Summary

  Constructors
  Constructor | Description
  --- | ---
  `ComponentHandler()` |

- ## Method Summary

  Modifier and Type | Method | Description
  --- | --- | ---
  `void` | `actionPerformed​(ActionEvent ae)` | Public as a result of Timer.
  `protected JScrollPane` | `getScrollPane()` | Returns the `JScrollPane` housing the `JTree`, or null if one isn't found.
  `protected void` | `startTimer()` | Creates, if necessary, and starts a Timer to check if need to resize the bounds.

  ### Methods declared in class java.awt.event.ComponentAdapter

  `componentHidden, componentMoved, componentResized, componentShown`

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

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

- ## Field Details

  - ### timer

    protected Timer timer
    Timer used when inside a scrollpane and the scrollbar is adjusting.

  - ### scrollBar

    protected JScrollBar scrollBar
    ScrollBar that is being adjusted.

- ## Constructor Details

  - ### ComponentHandler

    public ComponentHandler()

- ## Method Details

  - ### startTimer

    protected void startTimer()
    Creates, if necessary, and starts a Timer to check if need to resize the bounds.

  - ### getScrollPane

    protected JScrollPane getScrollPane()
    Returns the `JScrollPane` housing the `JTree`, or null if one isn't found.
    Returns:
      the `JScrollPane` housing the `JTree`

  - ### actionPerformed

    public void actionPerformed​(ActionEvent ae)
    Public as a result of Timer. If the scrollBar is null, or not adjusting, this stops the timer and updates the sizing.
    Specified by:
      `actionPerformed` in interface `ActionListener`
    Parameters:
      `ae` - the event to be processed