TreeMultiSelectExample.java
package com.itmill.toolkit.demo.sampler.features.trees;

import java.util.Iterator;
import java.util.Set;

import com.itmill.toolkit.data.Item;
import com.itmill.toolkit.data.Property.ValueChangeEvent;
import com.itmill.toolkit.data.Property.ValueChangeListener;
import com.itmill.toolkit.demo.sampler.ExampleUtil;
import com.itmill.toolkit.event.Action;
import com.itmill.toolkit.ui.AbstractSelect;
import com.itmill.toolkit.ui.Button;
import com.itmill.toolkit.ui.Tree;
import com.itmill.toolkit.ui.VerticalLayout;
import com.itmill.toolkit.ui.Button.ClickEvent;

public class TreeMultiSelectExample extends VerticalLayout implements
        Action.Handler {

    private static final Action ACTION_ADD = new Action("Add child item");
    private static final Action ACTION_DELETE = new Action("Delete");
    private static final Action[] ACTIONS = new Action[] { ACTION_ADD,
            ACTION_DELETE };

    private Tree tree;
    private Button deleteButton;

    public TreeMultiSelectExample() {
        setSpacing(true);

        // Create new Tree object using a hierarchical container from
        // ExampleUtil class
        tree = new Tree("Hardware Inventory", ExampleUtil
                .getHardwareContainer());
        // Set multiselect mode
        tree.setMultiSelect(true);
        tree.setImmediate(true);
        tree.addListener(new ValueChangeListener() {
            public void valueChange(ValueChangeEvent event) {
                Tree t = (Treeevent.getProperty();
                // enable if something is selected, returns a set
                deleteButton.setEnabled(t.getValue() != null
                        && ((Sett.getValue()).size() 0);
            }
        });

        // Add Actionhandler
        tree.addActionHandler(this);

        // Set tree to show the 'name' property as caption for items
        tree.setItemCaptionPropertyId(ExampleUtil.hw_PROPERTY_NAME);
        tree.setItemCaptionMode(AbstractSelect.ITEM_CAPTION_MODE_PROPERTY);

        // Expand whole tree
        for (Iterator it = tree.rootItemIds().iterator(); it.hasNext();) {
            tree.expandItemsRecursively(it.next());
        }

        // Create the 'delete button', inline click-listener
        deleteButton = new Button("Delete"new Button.ClickListener() {
            public void buttonClick(ClickEvent event) {
                // Delete all the selected objects
                Object[] toDelete = ((Set<Object>tree.getValue()).toArray();
                for (int i = 0; i < toDelete.length; i++) {
                    handleAction(ACTION_DELETE, tree, toDelete[i]);
                }
            }
        });
        deleteButton.setEnabled(false);

        addComponent(deleteButton);
        addComponent(tree);

    }

    /*
     * Returns the set of available actions
     */
    public Action[] getActions(Object target, Object sender) {
        return ACTIONS;
    }

    /*
     * Handle actions
     */
    public void handleAction(Action action, Object sender, Object target) {
        if (action == ACTION_ADD) {
            // Allow children for the target item
            tree.setChildrenAllowed(target, true);

            // Create new item, disallow children, add name, set parent
            Object itemId = tree.addItem();
            tree.setChildrenAllowed(itemId, false);
            String newItemName = "New Item # " + itemId;
            Item item = tree.getItem(itemId);
            item.getItemProperty(ExampleUtil.hw_PROPERTY_NAME).setValue(
                    newItemName);
            tree.setParent(itemId, target);
            tree.expandItem(target);
        else if (action == ACTION_DELETE) {
            Object parent = tree.getParent(target);
            tree.removeItem(target);
            // If the deleted object's parent has no more children, set it's
            // childrenallowed property to false
            if (parent != null && tree.getChildren(parent).size() == 0) {
                tree.setChildrenAllowed(parent, false);
            }
        }
    }
}