前序遍历构造已知二叉树(Java)

 1 public BiNode createBiTree()
 2 {
 3     Scanner input = new Scanner(System.in);
 4     int k = input.nextInt();
 5     if(k == -1)
 6         return null;
 7         
 8     BiNode node = new BiNode(k);
 9     node.lchild = createBiTree();
10     node.rchild = createBiTree();
11     return node;
12 }
13 
14 public static void main(String[] args)
15 {
16     BiTree t = new BiTree();
17     t.root = t.createBiTree();  //Java的方法均为按值传递 故应该有返回值(不同于C++) 
18 }