动手写一颗二叉树

二叉树的遍历，查找，删除等等

说到二叉树一般都跟递归有比较大的关系
数据结构如下：

package data_structrue;

/**
 * Created by hushangjie on 2017/11/10. 
*/
 public class BinaryTreeNode {
    private int data;
    private BinaryTreeNode leftChild;
    private BinaryTreeNode rightChild;

    public void setData(int data) {
        this.data = data;
    }

    public void setLeftChild(BinaryTreeNode leftChild) {
        this.leftChild = leftChild;
    }

    public void setRightChild(BinaryTreeNode rightChild) {
        this.rightChild = rightChild;
    }

    public int getData() {

        return data;
    }

    public BinaryTreeNode getLeftChild() {
        return leftChild;
    }

    public BinaryTreeNode getRightChild() {
        return rightChild;

    }
}

package data_structrue;

/**
 * Created by hushangjie on 2017/11/10. 
 */
public class BinaryTree {
    private BinaryTreeNode root;

    public BinaryTree() {
    }

    public BinaryTree(BinaryTreeNode root) {
        this.root = root;
    }

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

    public BinaryTreeNode getRoot() {

        return root;
    }

    //clear
  public void clear(BinaryTreeNode node) {
        if (node != null) {
            clear(node.getLeftChild());
            clear(node.getRightChild());
            node = null;
        }
    }

    //clear root
  public void clear() {
        clear(root);
    }

    //
  public boolean isEmpty() {
        return root == null;
    }

    //求二叉树的高度
  public int height() {
        return height(root);
    }

    public int height(BinaryTreeNode node) {
        if (node == null) {
            return 0;
        } else {
            int l = height(node.getLeftChild());
            int r = height(node.getRightChild());
            return l < r ? r + 1 : l + 1;
        }
    }

    //获取二叉树的总节点数
  public int size() {
        return size(root);
    }

    public int size(BinaryTreeNode node) {
        if (node == null) {
            return 0;
        } else {
            return 1 + size(node.getLeftChild()) + size(node.getRightChild());
        }
    }

    //先根遍历
  public void preOrder(BinaryTreeNode node){
        if (node != null) {
            System.out.println(node.getData());
            preOrder(node.getLeftChild());
            preOrder(node.getRightChild());
        }
    }

    //中跟遍历
  public void inOrder(BinaryTreeNode node) {
        if (node != null) {
            inOrder(node.getLeftChild());
            System.out.println(node.getData());
            inOrder(node.getRightChild());
        }
    }
    //后根遍历
  public void postOrder(BinaryTreeNode node){
        if (node != null) {
            preOrder(node.getLeftChild());
            preOrder(node.getRightChild());
            System.out.println(node.getData());
        }
    }

}