Module java.desktop
Package javax.swing

Class JTree

  • All Implemented Interfaces:
    ImageObserver, MenuContainer, Serializable, Accessible, Scrollable
    @JavaBean(defaultProperty="UI",
          description="A component that displays a set of hierarchical data as an outline.")
public class JTree
extends JComponent
implements Scrollable, Accessible
    A control that displays a set of hierarchical data as an outline. You can find task-oriented documentation and examples of using trees in How to Use Trees, a section in The Java Tutorial.

    A specific node in a tree can be identified either by a TreePath (an object that encapsulates a node and all of its ancestors), or by its display row, where each row in the display area displays one node. An expanded node is a non-leaf node (as identified by TreeModel.isLeaf(node) returning false) that will displays its children when all its ancestors are expanded. A collapsed node is one which hides them. A hidden node is one which is under a collapsed ancestor. All of a viewable nodes parents are expanded, but may or may not be displayed. A displayed node is both viewable and in the display area, where it can be seen.

    The following JTree methods use "visible" to mean "displayed":
    • isRootVisible()
    • setRootVisible()
    • scrollPathToVisible()
    • scrollRowToVisible()
    • getVisibleRowCount()
    • setVisibleRowCount()
    The next group of JTree methods use "visible" to mean "viewable" (under an expanded parent):
    • isVisible()
    • makeVisible()
    If you are interested in knowing when the selection changes implement the TreeSelectionListener interface and add the instance using the method addTreeSelectionListener. valueChanged will be invoked when the selection changes, that is if the user clicks twice on the same node valueChanged will only be invoked once.

    If you are interested in detecting either double-click events or when a user clicks on a node, regardless of whether or not it was selected, we recommend you do the following: 

     final JTree tree = ...;

 MouseListener ml = new MouseAdapter() {
     public void mousePressed(MouseEvent e) {
         int selRow = tree.getRowForLocation(e.getX(), e.getY());
         TreePath selPath = tree.getPathForLocation(e.getX(), e.getY());
         if(selRow != -1) {
             if(e.getClickCount() == 1) {
                 mySingleClick(selRow, selPath);
             }
             else if(e.getClickCount() == 2) {
                 myDoubleClick(selRow, selPath);
             }
         }
     }
 };
 tree.addMouseListener(ml);
    NOTE: This example obtains both the path and row, but you only need to get the one you're interested in.

    To use JTree to display compound nodes (for example, nodes containing both a graphic icon and text), subclass TreeCellRenderer and use setCellRenderer(javax.swing.tree.TreeCellRenderer) to tell the tree to use it. To edit such nodes, subclass TreeCellEditor and use setCellEditor(javax.swing.tree.TreeCellEditor).

    Like all JComponent classes, you can use InputMap and ActionMap to associate an Action object with a KeyStroke and execute the action under specified conditions.

    Warning: Swing is not thread safe. For more information see Swing's Threading Policy.

    Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeans™ has been added to the java.beans package. Please see XMLEncoder.

    Since:
    1.2
    See Also:
    Serialized Form