关键代码：

public void PopulateTreeMap(Hashtable wordsHash, Hashtable stemmedWordsHash)
{
    AssertValid();

    ArrayList nodes = new ArrayList();
    ArrayList aKeys = new ArrayList(stemmedWordsHash.Keys);
    aKeys.Sort();

    foreach (string key in aKeys)
    {
        //build each node element

        int count = (int)stemmedWordsHash[key];
        string name = (string)wordsHash[key];

        //show count in node?

        if(m_bShowWordCount)
            name += String.Format(" ({0})", count);
        NodeInfo nodeinfo = new NodeInfo(name, count);
        nodes.Add(nodeinfo);
    }
    m_nodes = nodes;
    RepopulateTreeMap();
}