TreeExpansionListener (Java SE 11 & JDK 11 )

All Superinterfaces:

EventListener

All Known Implementing Classes:

BasicTreeUI.TreeExpansionHandler, JTree.AccessibleJTree
```
public interface TreeExpansionListener
extends EventListener
```
The listener that's notified when a tree expands or collapses a node. For further documentation and examples see How to Write a Tree Expansion Listener, a section in The Java Tutorial.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`treeCollapsed(TreeExpansionEvent event)`	Called whenever an item in the tree has been collapsed.
`void`	`treeExpanded(TreeExpansionEvent event)`	Called whenever an item in the tree has been expanded.

- Method Detail
  - treeExpanded
```
void treeExpanded(TreeExpansionEvent event)
```
    Called whenever an item in the tree has been expanded.
    
    Parameters:
    
    event - a TreeExpansionEvent containing a TreePath object for the expanded node
  - treeCollapsed
```
void treeCollapsed(TreeExpansionEvent event)
```
    Called whenever an item in the tree has been collapsed.
    
    Parameters:
    
    event - a TreeExpansionEvent containing a TreePath object for the collapsed node