判断二叉树是否平衡，平衡并返回高度

public class IsBalanceTree {
	static class Node{
		int value;
		Node left;
		Node right;
		public Node(int data) {
			value = data;
		}
	}
	static class ReturnData{
		boolean isB;
		int level;
		public ReturnData(boolean isB, int level) {
			this.isB = isB;
			this.level = level;
		}
	}
	public static ReturnData isBalance(Node head) {
		if(head == null) {
			return new ReturnData(true,0);
		}
		ReturnData left = isBalance(head.left);
		if(!left.isB) {
			return new ReturnData(false,0);
		}
		ReturnData right = isBalance(head.right);
		if(!right.isB) {
			return new ReturnData(false,0);
		}
		if(Math.abs(left.level - right.level) > 1) {
			return new ReturnData(false,0);
		}
		return new ReturnData(true, Math.max(left.level, right.level) + 1);
	}
	public static void printIsBalance(ReturnData rd) {
		if(rd.isB) {
			System.out.println("true," + "level:" + rd.level);
		}else {
			System.out.println("false");
		}
	}
	
	//for test
	public static void main(String[] args) {
		Node head = null;
		printIsBalance(isBalance(head));;
		
		head = new Node(1);
		printIsBalance(isBalance(head));;
		
		head = new Node(1);
		head.left = new Node(2);
		head.right = new Node(3);
		head.left.left = new Node(4);
		head.left.left.left = new Node(5);
		printIsBalance(isBalance(head));;
		
		head = new Node(1);
		head.left = new Node(2);
		head.right = new Node(3);
		head.left.left = new Node(4);
		head.left.right = new Node(6);
		printIsBalance(isBalance(head));;
		
		
		head = new Node(100);
		head.left = new Node(21);
		head.left.left = new Node(37);
		head.right = new Node(-42);
		head.right.left = new Node(0);
		head.right.right = new Node(666);
		head.right.right.right = new Node(343432);
		head.right.right.right.right = new Node(4343434);
		printIsBalance(isBalance(head));;
	}
	
}