顺序存储二叉树（Java代码实现）

package Tree;

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

    }
}

//编写一个ArrayBinaryTree，实现顺序存储二叉树

class ArrayBinarTree {
    private int[] arr;//存储数据节点

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

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

    public void infixOrder(){
        this.infixOrder(0);
    }
    public void postOrder(){
        this.postOrder(0);
    }
    //编写一个方法.完成顺序存储二叉树的一个前序遍历
    //index表示数组的下标
    public void preOrder(int index) {
        //若果数组为空，或者arr.length = 0
        if (arr.length == 0 || arr == null) {
            System.out.println("数组为空，不能按照二叉树前序遍历");
        }
        //输出当前这个元素
        System.out.print(arr[index] + " ");
        //左递归
        if (2 * index + 1 < arr.length) {
            preOrder(2 * index + 1);
        }
        //右递归
        if (2 * index + 2 < arr.length) {
            preOrder(2 * index + 2);
        }
    }
    public void infixOrder(int index) {
        //若果数组为空，或者arr.length = 0
        if (arr.length == 0 || arr == null) {
            System.out.println("数组为空，不能按照二叉树前序遍历");
        }
        //左递归
        if (2 * index + 1 < arr.length) {
            infixOrder(2 * index + 1);
        }
        System.out.print(arr[index] + " ");
        //右递归
        if (2 * index + 2 < arr.length) {
            infixOrder(2 * index + 2);
        }
    }
    public void postOrder(int index) {
        //若果数组为空，或者arr.length = 0
        if (arr.length == 0 || arr == null) {
            System.out.println("数组为空，不能按照二叉树前序遍历");
        }

        //左递归
        if (2 * index + 1 < arr.length) {
            postOrder(2 * index + 1);
        }
        //右递归
        if (2 * index + 2 < arr.length) {
            postOrder(2 * index + 2);
        }
        //输出当前这个元素
        System.out.print(arr[index] + " ");
    }
}