Eclipse Plug-in Developer Guide (Galileo) - TreeStructureAdvisor (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.jface.databinding.viewers
Class TreeStructureAdvisor


java.lang.Object
  
org.eclipse.jface.databinding.viewers.TreeStructureAdvisor

public abstract class TreeStructureAdvisor
extends Object
extends Object

Instances of this class can be used to improve accuracy and performance of an ObservableListTreeContentProvider or an ObservableSetTreeContentProvider. This class is intended to be subclassed by clients.

Since:: 1.2

Constructor Summary

TreeStructureAdvisor ()


Method Summary

Object getParent ( Object element)
          Returns the parent for the given element, or null indicating that the parent can't be computed.

Boolean hasChildren ( Object element)
          Returns whether the given element has children, or null if the actual children collection should be consulted.

Methods inherited from class java.lang. Object

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

Constructor Detail

TreeStructureAdvisor

public TreeStructureAdvisor()

Method Detail

getParent

public 
Object getParent(
Object element)

Returns the parent for the given element, or null indicating that the parent can't be computed. In this case the tree-structured viewer can't expand a given node correctly if requested. The default implementation returns null; clients should override.

Parameters:: element - the element
Returns:: the parent element, or null if it has none or if the parent cannot be computed

hasChildren

public 
Boolean hasChildren(
Object element)

Returns whether the given element has children, or null if the actual children collection should be consulted. The default implementation returns null; clients should override.

Intended as an optimization for when the viewer does not need the actual children. Clients may be able to implement this more efficiently than getChildren.

Parameters:: element - the element
Returns:: Boolean.TRUE if the given element has children, Boolean.FALSE if the given element never has children, or null if the children collection should be consulted.