二叉排序树递归实现

public class BinarySortTreeDemo {

    public static void main(String[] args) {
        int[] array = {7, 3, 10, 12, 5, 1, 9};
        BinaryTree binaryTree = new BinaryTree();
        for (int i = 0; i < array.length; i++) {
            binaryTree.add(new Node(array[i]));
        }
        binaryTree.infixOrder();
    }

}

class BinaryTree {
    private Node root;

    public void add(Node node) {
        if(this.root == null) {
            root = node;
        } else {
            root.add(node);
        }
    }

    public void infixOrder() {
        if(root != null) {
            root.infixOrder();
        } else {
            System.out.println("二叉树为空~");
        }
    }
}

class Node {
    public int num;
    public Node left;
    public Node right;

    public Node(int num) {
        this.num = num;
    }

    @Override
    public String toString() {
        return num + "";
    }

    public void infixOrder() {
        if (this.left != null) {
            this.left.infixOrder();
        }
        System.out.print("=>" + this);
        if (this.right != null) {
            this.right.infixOrder();
        }
    }

    public void add(Node node) {
        if(node == null) {
            return;
        }
        if(node.num < this.num) {
            if(this.left != null) {
                this.left.add(node);
            } else {
                this.left = node;
            }
        } else {
            if(this.right != null) {
                this.right.add(node);
            } else {
                this.right = node;
            }
        }
    }
}