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()`
Constructs a `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()
Constructs a `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