JAVA判断二叉树是否是二叉平衡树

import java.util.*;      
     
public class BinaryTree {      
    protected Node root;      
     
    public BinaryTree(Node root) {      
        this.root = root;      
    }      
     
    public Node getRoot() {      
        return root;      
    }      
     
    /** 构造树 */     
    public static Node init() {      
        Node a = new Node('A');      
        Node b = new Node('B', null, a);      
        Node c = new Node('C');      
        Node d = new Node('D', b, c);      
        Node e = new Node('E');      
        Node f = new Node('F', e, null);      
        Node g = new Node('G', null, f);      
        Node h = new Node('H', d, g);      
        return h;// root      
    }      

/**
  * 返回树的层数
  * 
  * @param p
  * @return
  */
 public static int h(Node p) {

  if (p == null)
   return -1;
  return 1 + Math.max(h(p.getLeft()), h(p.getRight()));// 返回较大的
 }

 /**
  * 检查是否是平衡树
  * 
  * @param p
  * @return
  */
 public static boolean checkAVL(Node p) {

  if (p == null)
   return true;
  // 左子树与右子树绝对值不能超过 1，并且左右子树也是平衡二叉树
  return (Math.abs(h(p.getLeft()) - h(p.getRight())) <= 1 && checkAVL(p.getLeft()) && checkAVL(p.getRight()));

 }

  
    /**    
     * @param args    
     */     
    public static void main(String[] args) {      
        BinaryTree tree = new BinaryTree(init());      
        
         System.out.println("是否是平衡树");  
         System.out.println(checkAVL(tree.getRoot()));
    }   

    
     
}     
 class Node {      
    private char key;      
    private Node left, right;      
     
    public Node(char key) {      
        this(key, null, null);      
    }      
     
    public Node(char key, Node left, Node right) {      
        this.key = key;      
        this.left = left;      
        this.right = right;      
    }      
     
    public char getKey() {      
        return key;      
    }      
     
    public void setKey(char key) {      
        this.key = key;      
    }      
     
    public Node getLeft() {      
        return left;      
    }      
     
    public void setLeft(Node left) {      
        this.left = left;      
    }      
     
    public Node getRight() {      
        return right;      
    }      
     
    public void setRight(Node right) {      
        this.right = right;      
    }      
}   

C:\ex>java   BinaryTree
是否是平衡树
false