Java 二叉樹的實現以及遍歷

import java.util.LinkedList;
import java.util.List;

/**
 * Created by yhq on 2016/4/11.
 */
public class BinTree{

    private static int[] array = {1, 2, 3, 4, 5, 6, 7, 8, 9};
    private static List<Node> nodeList = null;

    public static void createBinTree() {
        nodeList = new LinkedList<Node>();

        //放到鏈表中
        for (int arr : array) {
            nodeList.add(new Node(arr));
        }

        // 對前lastParentIndex-1個父節點按照父節點與孩子節點的數字關係建立二叉樹
        for (int parentIndex = 0; parentIndex < array.length / 2 - 1; parentIndex++) {
            // 左孩子
            nodeList.get(parentIndex).leftNode = nodeList.get(parentIndex * 2 + 1);
            // 右孩子
            nodeList.get(parentIndex).rightNode = nodeList.get(parentIndex * 2 + 2);
        }

        // 最後一個父節點:因爲最後一個父節點可能沒有右孩子，所以單獨拿出來處理
        int lastParentIndex = array.length / 2 - 1;
        // 左孩子
        nodeList.get(lastParentIndex).leftNode = nodeList.get(lastParentIndex * 2 + 1);
        // 右孩子,如果數組的長度爲奇數才建立右孩子
        if (array.length % 2 == 1) {
            nodeList.get(lastParentIndex).rightNode = nodeList.get(lastParentIndex * 2 + 2);
        }

    }

    private static class Node {
        Node leftNode;
        Node rightNode;
        int data;

        private Node(int data) {
            leftNode = null;
            rightNode = null;
            this.data = data;
        }
    }


    /**
     * 先續遍歷
     */
    public static void preOrderTraverse(Node node) {
        if (node == null) {
            return;
        }
        System.out.print(node.data + "\t");
        preOrderTraverse(node.leftNode);
        preOrderTraverse(node.rightNode);
    }

    public static void sufOrderTraverse(Node node){
        if(node==null){
            return ;
        }
        sufOrderTraverse(node.rightNode);
        System.out.print(node.data);
        sufOrderTraverse(node.leftNode);
    }

    public static void inOrderTraverse(Node node){
        if(node==null){
            return ;
        }
        inOrderTraverse(node.leftNode);
        System.out.print(node.data);
        inOrderTraverse(node.rightNode);
    }

    public static void main(String[] args) {
        BinTree tree = new BinTree();
        tree .createBinTree();
        Node root = nodeList.get(0);
        preOrderTraverse(root);
        inOrderTraverse(root);
        sufOrderTraverse(root);
    }

}