Java/GWT/Tree

Create Tree With Pending Item

package com.jexp.gwt.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;
import com.google.gwt.user.client.ui.Tree;
import com.google.gwt.user.client.ui.TreeItem;
import com.google.gwt.user.client.ui.TreeListener;
public class GWTClient implements EntryPoint,TreeListener {
  class PendingItem extends TreeItem {
    public PendingItem() {
      super("Please wait...");
    }
  }
  class TreeNode {
    public TreeNode[] children;
    public TreeItem item;
    public String text;
    public TreeNode(String text) {
      this.text = text;
    }
    public TreeNode(String text, TreeNode[] children) {
      this(text);
      this.children = children;
    }
  }
  TreeNode[] fTreeNode = new TreeNode[]{
    new TreeNode("A", new TreeNode[]{
      new TreeNode("B", new TreeNode[]{
        new TreeNode("1"), 
        new TreeNode("2"),
        new TreeNode("3"), 
        new TreeNode("4"),
        new TreeNode("5"),}),
      new TreeNode("B", new TreeNode[]{
        new TreeNode("B1"), 
        new TreeNode("B2"),
        new TreeNode("B3"),}),
      new TreeNode("C", new TreeNode[]{
        new TreeNode("C1"), 
        new TreeNode("C2"),}),
      new TreeNode("D", new TreeNode[]{
        new TreeNode("1"), 
        new TreeNode("2"),
        new TreeNode("3"),}),}),
    new TreeNode("AA", new TreeNode[]{
      new TreeNode("A", new TreeNode[]{
        new TreeNode("A1"), 
        new TreeNode("A2"),
        new TreeNode("A3"),
        new TreeNode("A4"),}),
      new TreeNode("B", new TreeNode[]{
        new TreeNode("1"),
        new TreeNode("2"),
        new TreeNode("3"),
        new TreeNode("4"),}),
      new TreeNode("C", new TreeNode[]{
        new TreeNode("F"),
        new TreeNode("E"),}),
      new TreeNode("G", new TreeNode[]{
        new TreeNode("C"), 
        new TreeNode("2"),
        new TreeNode("F"), 
        new TreeNode("E"),}),}),
    new TreeNode("M", new TreeNode[]{
        new TreeNode("C", new TreeNode[]{
      new TreeNode("P"), 
      new TreeNode("V"),}),}),};
  public void onModuleLoad() {
    Tree tree = new Tree();
    for (int i = 0; i < fTreeNode.length; ++i) {
      createItem(fTreeNode[i]);
      tree.addItem(fTreeNode[i].item);
    }
    tree.addTreeListener(this);
    tree.setWidth("20em");
    RootPanel.get().add(tree);
  }
  private void createItem(TreeNode TreeNode) {
    TreeNode.item = new TreeItem(TreeNode.text);
    TreeNode.item.setUserObject(TreeNode);
    if (TreeNode.children != null) {
      TreeNode.item.addItem(new PendingItem());
    }
  }
  public void onTreeItemSelected(TreeItem item) {
    Window.alert(((TreeNode) item.getUserObject()).text);
  }
  public void onTreeItemStateChanged(TreeItem item) {
    TreeItem child = item.getChild(0);
    if (child instanceof PendingItem) {
      item.removeItem(child);
      TreeNode tn = (TreeNode) item.getUserObject();
      for (int i = 0; i < tn.children.length; ++i) {
        createItem(tn.children[i]);
        item.addItem(tn.children[i].item);
      }
    }
  }
  
}

Use TreeListener

package com.jexp.gwt.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Button;
import com.google.gwt.user.client.ui.ClickListener;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.Widget;
import com.google.gwt.user.client.ui.Tree;
import com.google.gwt.user.client.ui.TreeItem;
import com.google.gwt.user.client.ui.TreeListener;
public class GWTClient implements EntryPoint,TreeListener {
  class PendingItem extends TreeItem {
    public PendingItem() {
      super("Please wait...");
    }
  }
  class TreeNode {
    public TreeNode[] children;
    public TreeItem item;
    public String text;
    public TreeNode(String text) {
      this.text = text;
    }
    public TreeNode(String text, TreeNode[] children) {
      this(text);
      this.children = children;
    }
  }
  TreeNode[] fTreeNode = new TreeNode[]{
    new TreeNode("A", new TreeNode[]{
      new TreeNode("B", new TreeNode[]{
        new TreeNode("1"), 
        new TreeNode("2"),
        new TreeNode("3"), 
        new TreeNode("4"),
        new TreeNode("5"),}),
      new TreeNode("B", new TreeNode[]{
        new TreeNode("B1"), 
        new TreeNode("B2"),
        new TreeNode("B3"),}),
      new TreeNode("C", new TreeNode[]{
        new TreeNode("C1"), 
        new TreeNode("C2"),}),
      new TreeNode("D", new TreeNode[]{
        new TreeNode("1"), 
        new TreeNode("2"),
        new TreeNode("3"),}),}),
    new TreeNode("AA", new TreeNode[]{
      new TreeNode("A", new TreeNode[]{
        new TreeNode("A1"), 
        new TreeNode("A2"),
        new TreeNode("A3"),
        new TreeNode("A4"),}),
      new TreeNode("B", new TreeNode[]{
        new TreeNode("1"),
        new TreeNode("2"),
        new TreeNode("3"),
        new TreeNode("4"),}),
      new TreeNode("C", new TreeNode[]{
        new TreeNode("F"),
        new TreeNode("E"),}),
      new TreeNode("G", new TreeNode[]{
        new TreeNode("C"), 
        new TreeNode("2"),
        new TreeNode("F"), 
        new TreeNode("E"),}),}),
    new TreeNode("M", new TreeNode[]{
        new TreeNode("C", new TreeNode[]{
      new TreeNode("P"), 
      new TreeNode("V"),}),}),};
  public void onModuleLoad() {
    Tree tree = new Tree();
    for (int i = 0; i < fTreeNode.length; ++i) {
      createItem(fTreeNode[i]);
      tree.addItem(fTreeNode[i].item);
    }
    tree.addTreeListener(this);
    tree.setWidth("20em");
    RootPanel.get().add(tree);
  }
  private void createItem(TreeNode TreeNode) {
    TreeNode.item = new TreeItem(TreeNode.text);
    TreeNode.item.setUserObject(TreeNode);
    if (TreeNode.children != null) {
      TreeNode.item.addItem(new PendingItem());
    }
  }
  public void onTreeItemSelected(TreeItem item) {
    Window.alert(((TreeNode) item.getUserObject()).text);
  }
  public void onTreeItemStateChanged(TreeItem item) {
    TreeItem child = item.getChild(0);
    if (child instanceof PendingItem) {
      item.removeItem(child);
      TreeNode tn = (TreeNode) item.getUserObject();
      for (int i = 0; i < tn.children.length; ++i) {
        createItem(tn.children[i]);
        item.addItem(tn.children[i].item);
      }
    }
  }
  
}