Java数组实现顺序存储二叉树进行前中后序遍历

/** 用数组实现顺序存储完全二叉树，并进行前序遍历中序遍历后序遍历 *         1 *       /  \ *      2    3 *     / \  / *    4  5 6 */public class ArrayBinaryTreeDemo {    public static void main(String[] args) {        int[] tree = {1, 2, 3, 4, 5, 6};        ArrayBinaryTree arrayBinaryTree = new ArrayBinaryTree(tree);        arrayBinaryTree.preOrder();   // 1 2 4 5 3 6        arrayBinaryTree.infixOrder(); // 4 2 5 1 6 3        arrayBinaryTree.postOrder();  // 4 5 2 6 3 1    }}class ArrayBinaryTree {    private int[] arr;    public ArrayBinaryTree(int[] arr) {        this.arr = arr;    }    /**     * 先序遍历     */    public void preOrder() {        if (arr == null || arr.length == 0) {            System.out.println("树为空！");            return;        }        preOrder(0);        System.out.println();    }    /**     * 中序遍历     */    public void infixOrder() {        if (arr == null || arr.length == 0) {            System.out.println("树为空！");            return;        }        infixOrder(0);        System.out.println();    }    /**     * 后序遍历     */    public void postOrder() {        if (arr == null || arr.length == 0) {            System.out.println("树为空！");            return;        }        postOrder(0);        System.out.println();    }    private void infixOrder(int index) {        int left = index * 2 + 1; // 左子节点index        if (left < arr.length) infixOrder(left);        System.out.print(arr[index] + " ");        int right = index * 2 + 2; // 右子节点index        if (right < arr.length) infixOrder(right);    }    private void postOrder(int index) {        int left = index * 2 + 1;        if (left < arr.length) postOrder(left);        int right = index * 2 + 2;        if (right < arr.length) postOrder(right);        System.out.print(arr[index] + " ");    }    private void preOrder(int index) {        System.out.print(arr[index] + " ");        int left = index * 2 + 1;        if (left < arr.length) {            preOrder(left);        }        int right = index * 2 + 2;        if (right < arr.length) {            preOrder(right);        }    }}