二叉树操作

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

class BTree {
  String data = null;
  BTree rightChild = null;
  BTree leftChild = null;
}

public class Tree {

  static void preOrder(BTree root) {

    if (root == null) {
      return;
    }
    System.out.print(root.data);
    preOrder(root.leftChild);
    preOrder(root.rightChild);

  }

  static void inOrder(BTree root) {

    if (root == null) {
      return;
    }
    inOrder(root.leftChild);
    System.out.print(root.data);
    inOrder(root.rightChild);

  }

  static BTree createTree(BTree root) {
    String c = null;
    System.out.print("请输入一个字符型：");
    BufferedReader strin = new BufferedReader(new InputStreamReader(
        System.in));
    try {
      c = strin.readLine();
    } catch (IOException e) {
      e.printStackTrace();
    }
    if (c.equals("#")) {
      root = null;
    } else {
      root = new BTree();
      root.data = c;
      root.leftChild = new BTree();
      root.rightChild = new BTree();
      root.leftChild = createTree(root.leftChild);
      root.rightChild = createTree(root.rightChild);
    }
    return root;

  }

  static BTree createTree() {
    String c = null;
    System.out.print("请输入一个字符型：");
    BufferedReader strin = new BufferedReader(new InputStreamReader(
        System.in));
    try {
      c = strin.readLine();
    } catch (IOException e) {
      e.printStackTrace();
    }
    BTree root = new BTree();
    if (c.equals("#")) {
      root = null;
    } else {
      root.data = c;
      root.leftChild = createTree();
      root.rightChild = createTree();
    }
    return root;

  }

  static BTree createTree(String str, int current) {

    char c = str.charAt(current);

    BTree root = new BTree();
    if (c == '#') {
      root = null;
    } else {
      root.data = String.valueOf(c);
      root.leftChild = createTree(str, current * 2 + 1);
      root.rightChild = createTree(str, current * 2 + 2);
    }
    return root;

  }

  static int depth(BTree root) {
    int result=0;
    int left=0;
    int right=0;
    if (root != null) {
    
      if (root.leftChild != null){
         left = depth(root.leftChild);}
      if (root.rightChild != null){
         right = depth(root.rightChild);}
      if (left > right) {
        result= left + 1;
      } else {
        result= right + 1;
      }
    }
    return result;
  }

  public static void main(String args[]) throws IOException {

    BTree root = null;
    String str = "ABCD#####";
    root = createTree(str, 0);
    System.out.println("-------------------------");
    preOrder(root);
    System.out.println("\n-------------------------");
    inOrder(root);
    System.out.println("\n-------------------------");
    System.out.print(depth(root));
  }

}