RODTreeNodeData.java

package test.tree.rod;

import java.util.List;

/**
 * tested with ZK 6.0.2
 * 
 * The interface for data bean that used in RODTreeModel and RODTreeNode
 * 
 * @author benbai123
 *
 */
public class RODTreeNodeData {
  private Object _obj;
  // constructor
  public RODTreeNodeData (Object obj) {
    _obj = obj;
  }
  /**
   * get children of this data
   * @return
   */
  public List<? extends RODTreeNodeData> getChildren() {
    RODTreeNodeDataHelper.getChildrenOf(obj);
  }
  /**
   * get child count of this data, do not need to really get children
   * @return
   */
  public int getChildCount () {
    RODTreeNodeDataHelper.getChildCountOf(obj);
  }
}

RODTreeNodeDataHelper.java

package test.tree.rod;

import java.util.List;

public class RODTreeNodeDataHelper {
  // probably can cache children for reuse (Multiton Pattern)
  // remember to override hashCode and equals methods
  private Map<Object, List> _childrenCache = new HashMap<Object, List>();
  
  public static getChildCountOf (Object data) {
    // detect instance of data
    // access files or db to get child count of data
    // e.g.
    if (data instanceof File) {
      // operations for File class
      
      // probably can apply some other design patterns here
      // e.g. Chain of Responsibility or Strategy
    } else if (data instanceof Employee) {
      // operations for Employee class
    }
  }
  public static getChildrenOf (Object obj) {
    List children = new ArrayList();
    // some operations...
    // similar to getChildCountOf method
    // some operations...
    _childrenCache.put(obj, children)
    return children;
  }
}