import java.awt.*;
import javax.swing.*;
import javax.swing.tree.*;

/** Simple TreeNode that builds children on the fly.
 *  The key idea is that getChildCount is always called before
 *  any actual children are requested. That way, getChildCount 
 *  builds the children if they don't already exist.
 *  <P>
 *  In this case, it just builds an "outline" tree. I.e.,
 *  if the root is current node is "x", the children are
 *  "x.0", "x.1", "x.2", and "x.3".
 * <P>
 *
 *  Taken from Core Web Programming from 
 *  Prentice Hall and Sun Microsystems Press,
 *  http://www.corewebprogramming.com/.
 *  &copy; 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted. 
 */

public class OutlineNode extends DefaultMutableTreeNode {
  private boolean areChildrenDefined = false;
  private int outlineNum;
  private int numChildren;

  public OutlineNode(int outlineNum, int numChildren) {
    this.outlineNum = outlineNum;
    this.numChildren = numChildren;
  }
  
  public boolean isLeaf() {
    return(false);
  }

  public int getChildCount() {
    if (!areChildrenDefined) {
      defineChildNodes();
    }
    return(super.getChildCount());
  }

  private void defineChildNodes() {
    // You must set the flag before defining children if you
    // use "add" for the new children. Otherwise, you get an 
    // infinite recursive loop since add results in a call 
    // to getChildCount. However, you could use "insert" in such 
    // a case.
    areChildrenDefined = true;
    for(int i=0; i<numChildren; i++) {
      add(new OutlineNode(i+1, numChildren));
    }
  }

  public String toString() {
    TreeNode parent = getParent();
    if (parent == null) {
      return(String.valueOf(outlineNum));
    } else {
      return(parent.toString() + "." + outlineNum);
    }
  }
}