Controlling the display of objects as tree leaves

By default, the tree adapter considers an object to be a tree leaf when the method getContainerInterface returns null for that object.

You can have a finer control over whether an object should be considered as a tree leaf or not by means of the property expansion . By default, this property is set to the value ExpansionType.IN_PLACE , which produces the default behavior described earlier. To have an object considered as a leaf, even if the method getContainerInterface does not return null , you must set this property to ExpansionType.NO_EXPANSION . For information on how to set a property value, see Introducing cascading style sheets.