顺序存储二叉树

public class ArrBinaryTreeDemo {

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7};
        ArrBinaryTree arrBinaryTree = new ArrBinaryTree(arr);
        arrBinaryTree.preOrder();
        System.out.println();
        arrBinaryTree.infixOrder();
        System.out.println();
        arrBinaryTree.postOrder();
    }
}

class ArrBinaryTree {
    private int[] arr;//存储数据节点的数组

    public ArrBinaryTree(int[] arr) {
        this.arr = arr;
    }

    public void preOrder(){
        this.preOrder(0);
    }
    public void infixOrder(){
        this.infixOrder(0);
    }
    public void postOrder(){
        this.postOrder(0);
    }

    /**
     * @param index 数组下标
     */
    public void preOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空");
        }
        System.out.print(arr[index]);
        //向左递归
        if (index * 2 + 1 < arr.length) {
            preOrder(2 * index + 1);
        }
        //向右递归
        if (index * 2 + 2 < arr.length) {
            preOrder(2 * index + 2);
        }
    }
    public void infixOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空");
        }
        //向左递归
        if (index * 2 + 1 < arr.length) {
            infixOrder(2 * index + 1);
        }
        System.out.print(arr[index]);
        //向右递归
        if (index * 2 + 2 < arr.length) {
            infixOrder(2 * index + 2);
        }
    }
    public void postOrder(int index) {
        if (arr == null || arr.length == 0) {
            System.out.println("数组为空");
        }
        //向左递归
        if (index * 2 + 1 < arr.length) {
            postOrder(2 * index + 1);
        }
        //向右递归
        if (index * 2 + 2 < arr.length) {
            postOrder(2 * index + 2);
        }
        System.out.print(arr[index]);
    }
}