Java传入二叉树结点参数问题

[酸橙子不好吃]

创建了一个二叉树，在调用searchNode（）时出了问题，请问如何将二叉树结点参数传入方法呢？

//*************主方法******
public static void main(String [] args) {
		
	String preStr = "AB#DE###C##";
	BiTree T = new BiTree(preStr);

	BiTreeNode x = T.searchNode(T.getRoot(),'D');
	
	System.out.println(x.data);
}

//出的问题：Exception in thread "main" java.lang.NullPointerException



//***************二叉树结点******************************
public class BiTreeNode {
	public Object data;

	public BiTreeNode lchild, rchild; 

	public BiTreeNode() {
		this(null);
	}

	public BiTreeNode(Object data) {
		this(data, null, null);
	}

	public BiTreeNode(Object data, BiTreeNode lchild, BiTreeNode rchild) {
		this.data = data;
		this.lchild = lchild;
		this.rchild = rchild;
	}
}

//**********二叉树*********************
public class BiTree {

	public BiTreeNode root;

	public BiTree() {
		this.root = null;
	}

	public BiTree(BiTreeNode root) {
		this.root = root;
	}
	
	private static int index = 0;

	public BiTree(String preStr) {
		char c = preStr.charAt(index++);
		if (c != '#') {
			root = new BiTreeNode(c);
			root.lchild=new BiTree(preStr).root;
			root.rchild=new BiTree(preStr).root;
		} else
			root = null;
	}

        public BiTreeNode getRoot() {
		return root;
	}

	public void setRoot(BiTreeNode root) {
		this.root = root;
	}



	public BiTreeNode searchNode(BiTreeNode T,Object x) {
		if(T != null) {
			if(T.equals(x))
				return T;
			else {
				BiTreeNode lresult = searchNode (T.lchild,x);
				return lresult != null ? lresult : searchNode(T.rchild,x);
			}
		}
		return null;
	}


}

[伫望-向北]

最明显的一点是BiTreeNode 这个类没有重写equals方法，searchNode方法中T.equals(x)一直没false,另外你这个二叉树写的也有问题。