LongTree的正确分析理解

messageID	ParentMessageID	threadID	forumID
2	NULL	         1	31
31	2	         1	31
46	2	         1	31
61	2	         1	31
62	2	         1	31
32	31	         1	31
47	46	         1	31

public void addChild(long parentKey, long newKey)
  {
    //	找到一个给定的节点parentKey的父结点
    char parentIndex = findKey(parentKey, (char) 1);
    //System.out.println("父节点索引号:" + (int)parentIndex + "-----父结点:" + parentKey +
    //   "-----子结点:" + (int)newKey);
    if (parentIndex == 0)
    {
      throw new IllegalArgumentException("Parent key " + parentKey +
                                         " not found when adding child " +
                                         newKey + ".");
    }

    keys[nextIndex] = newKey;
    leftChildren[nextIndex] = 0;
    rightSiblings[nextIndex] = 0;
    System.out.println("keys[" + (int) nextIndex + "] = " + (int) newKey);

    // Adjust references. Check to see if the parent has any children.
    if (leftChildren[parentIndex] == 0)
    {
      // No children, therefore make the new key the first child.
      leftChildren[parentIndex] = nextIndex;
      System.out.println("leftChildren[" + (int) parentIndex + "] = " +
                         (int) nextIndex);
    }
    else
    {
      // The parent has children, so find the right-most child.
      long siblingIndex = leftChildren[parentIndex];

      while (rightSiblings[new Long(siblingIndex).intValue()] != 0)
      {
        siblingIndex = rightSiblings[new Long(siblingIndex).intValue()];
      }

      // Add the new entry as a sibling of that last child.

      //rightSiblings[new Long(siblingIndex).intValue()] = nextIndex;

      int tmpint = new Long(siblingIndex).intValue();
      rightSiblings[tmpint] = nextIndex ;
      System.out.println("rightSiblings[" + tmpint +"] = "  + (int)nextIndex);
    }

    // Finally, increment nextIndex so it's ready for next add.
    nextIndex++;
  }