Tree

The Tree component allows a natural way to represent data that has hierarchical relationships, such as filesystems or message threads. The Tree component in IT Mill Toolkit works much like the tree components of most modern desktop user interface toolkits, for example in directory browsing.

The most prominent use of the Tree component is to use it for displaying a hierachical menu, like the menu on the left side of the screen for instance or to display filesystems or other hierarchical datasets. The menu style makes the appearance of the tree more suitable for this purpose.

final Object[][] planets = new Object[][]{
        new Object[]{"Mercury"}, 
        new Object[]{"Venus"},
        new Object[]{"Earth", "The Moon"},    
        new Object[]{"Mars", "Phobos", "Deimos"},
        new Object[]{"Jupiter", "Io", "Europa", "Ganymedes", "Callisto"},
        new Object[]{"Saturn", "Titan", "Tethys", "Dione", "Rhea", "Iapetus"},
        new Object[]{"Uranus", "Miranda", "Ariel", "Umbriel", "Titania", "Oberon"},
        new Object[]{"Neptune", "Triton", "Proteus", "Nereid", "Larissa"}};
        
Tree tree = new Tree("The Planets and Major Moons");

/* Add planets as root items in the tree. */
for (int i=0; i<planets.length; i++) {
    String planet = (String) (planets[i][0]);
    tree.addItem(planet);
    
    if (planets[i].length == 1) {
        /* The planet has no moons so make it a leaf. */
        tree.setChildrenAllowed(planet, false);
    } else {
        /* Add children (moons) under the planets. */
        for (int j=1; j<planets[i].length; j++) {
            String moon = (String) planets[i][j];
            
            /* Add the item as a regular item. */
            tree.addItem(moon);
            
            /* Set it to be a child. */
            tree.setParent(moon, planet);
            
            /* Make the moons look like leaves. */
            tree.setChildrenAllowed(moon, false);
        }

        /* Expand the subtree. */
        tree.expandItemsRecursively(planet);
    }
}

main.addComponent(tree);

Figure 4.21. A Fully Expanded Tree

The Tree component uses Container data sources much like the Table component, with the addition that it also utilizes hierarchy information maintained by a container.