Building a binary tree from a string

Question

I'm having trouble building a binary tree with shape described in a string.
00 - means both left and right subtrees are empty;
01 - means that the left is empty, and the right is not;
10 - right is empty, left is not
11 - neither are empty
public BinaryTree(String s, Iterator it) {
This constructor is supposed to build the binary tree of the specified shape and fills it with values. THe values come from Iterator it, and are placed into the tree in preorder fashion.
I have to complete this constructor but I don't really know what to do. I was thinking I could use indexOf somehow. Any help would be greatly appreciated.
Thanks,
Mike

Answer 1

I'd build it like this (this is from the top of my head, so no typo-free-warranties etc.) -- public class Tree {
   private Object data;
   private Tree left= null;
   private Tree right= null;
   private Tree(StringReader sr, Iterator di) {
      char l= (char)sr.read(); // left and right subtree indicators
      char r= (char)sr.read();
      data= di.next(); // set data for this node
      if (l == '1') left= new Tree(sr, di); // build left subtree
      if (r == '1') right= new Tree(sr, di); // build right subtree
   public Tree(String s, Iterator di) {
      this(new StringReader(s), di);
} Note that the private constructor (the one that does all the work) doesn't handle incorrect strings
at all, i.e. it'll crash horribly when the string passes contains, say an odd number of characters
is is simply passing incorrect construction information. Also note that the Iterator must be able
to iterate over enough elements to be set.
kind regards,
Jos