Error in execution (but it compiles)

Question

This is a follow up from a previous question, but I started a new thread because its a new problem.
We are given a file with 99999 lines. Each line of the file represents a single node and it contains four integer: key, value, left child key, right child key (in the order specified). Key is a unique identifier assigned to each node. This identifier is just the line number. Value is the integer value stored in the node of the tree. Left and Right children are keys of the two appropriate children of the node. If a left or right child key is equal to zero, the appropriate child does not exist. The root node of the tree has key one.
Here are the first 10 lines, for example:
1 75 2 4
2 68 6 7
3 58 9 10
4 88 12 15
5 28 18 19
6 27 21 22
7 24 24 25
8 5 28 29
9 69 31 34
10 61 37 38
For example, the first line of the file is 1 75 2 4. It means that value of the node with key 1 is 75, key (line of file) of the left child of this node is 2, and key of right child is 4. Note: not all nodes in the file are part of the tree. Some lines in the file are there just to confuse you. What is the depth of this tree? (Depth is defined as the total number of nodes along the longest path.)
Now, I have some code I think will work. It compiles. It won't run though. Here is the code and below is what comes up in the command window:
import java.util.*;
import java.io.*;
class Depth
     static Scanner sc;
     static List<int[]> dump = new ArrayList<int[]>();
     public static void main(String[]args) throws Exception
          String filename = "src/data.txt";
          try
               sc = new Scanner(new File("tree.input"));
          catch (FileNotFoundException e)
          while(sc.hasNextLine())
               int[] row = new int[4];
               row[0] = sc.nextInt();
               row[1] = sc.nextInt();
               row[2] = sc.nextInt();
               row[3] = sc.nextInt();
               dump.add(row);
          TreeNode top = new TreeNode(dump.get(0)[1]);
          build(top, dump.get(0)[2], dump.get(0)[3]);
          System.out.println("The depth of the tree is " + top.depth() + ".");
     static TreeNode build(TreeNode n, int left_child_key, int right_child_key)
          TreeNode leftNode = new TreeNode(left_child_key);
          TreeNode rightNode = new TreeNode(right_child_key);
          if(left_child_key != -1)
               build(leftNode, getLeftChildKey(left_child_key), getRightChildKey(left_child_key));
               n.setLeft(leftNode);
          if(right_child_key != -1)
               build(rightNode, getLeftChildKey(right_child_key), getRightChildKey(right_child_key));
               n.setRight(rightNode);
          return n;
     static int getLeftChildKey(int key)
          for(int[] row: dump)
               if(row[0] == key)
               return row[2];
          return -1;
     static int getRightChildKey(int key)
     for(int[] row: dump)
               if(row[0] == key)
               return row[3];
     return -1;
class TreeNode
     int value;
     TreeNode leftChild, rightChild;
     TreeNode(int v)
          value = v;
     public void setLeft(TreeNode l)
          leftChild = l;
     public void setRight(TreeNode r)
          rightChild = r;
     public int depth()
          int ld = 0, rd = 0;
          if (leftChild != null) ld = leftChild.depth();
          if (rightChild != null) rd = rightChild.depth();
          return Math.max(ld, rd) + 1;
Exception in thread "main" java.util.NoSuchElementException
        at java.util.Scanner.throwFor(Unknown Source)
        at java.util.Scanner.next(Unknown Source)
        at java.util.Scanner.nextInt(Unknown Source)
        at java.util.Scanner.nextInt(Unknown Source)
        at HW.main(HW.java:26)Any Ideas? I need to execute this so I can find the depth. Thank you!

Answer 1

Turns out there was an empty line at the end of my huge file that kept it from working. It works now, but from what you guys can tell will it work for left or right children not being 0 (because they aren't supposed to exists if its 0)?
Edited by: Ravenatic20 on Apr 29, 2009 7:56 AM