前序遍历构造已知二叉树(Java)

 public BiTNode createBiTree()
 {
     Scanner input = new Scanner(System.in);
     int k = input.nextInt();
     if(k == -1)
         return null;

     BiTNode node = new BiTNode(k);
     node.lchild = createBiTree();
     node.rchild = createBiTree();
     return node;
 }

 public static void main(String[] args)
 {
     BiTree t = new BiTree();
     t.root = t.createBiTree();  //Java的方法均为按值传递 故应该有返回值(区别于C++)
 }