Thread: Problem with Binary Search Tree

Hi, I'm new to the forum and am not sure if this is the right place to post this, but I'm getting a problem with the following Binary Search Tree:

import java.awt.*;
import java.awt.event.*;
 
import javax.swing.*;
 
import java.util.Comparator;
class BST{
private BSTNode t=null;
private BSTNode l = null;
private BSTNode r = null;
private BSTNode node;
private StringComparator comp;// how to compare nodes
public BST(Comparator c){
 
 
}
 
// constructor
public BSTNode insert(Object newData){
BSTNode temp=t;
if (t == null)
{
    t=new BSTNode(newData);
    t.left= new BSTNode(null);
    t.right= new BSTNode(null);
    return t;
}
else
{
 
    while (temp.data != null)
    {
        if (comp.compare(temp.data, newData)<0)
            {
                System.out.println("going left");
                temp=temp.left;
            }
            else
            {
                System.out.println("going right");
                temp=temp.right;
            }
 
    }
    temp.data=newData;
    temp.left= new BSTNode(null);
    temp.right= new BSTNode(null);
    return temp;
}
//  if (comp.compare(t.data, newData)<0)
//  return t.left = insert(newData);
//else return t.right = insert(newData);
}
 
 
// can check if comp is null before insert
public void setComparator(StringComparator c){
if (t == null)
    c.compare(t.data, node.data);
}
// only allow if tree empty
public void clear(){
 
    t = null;
}// empty tree
public BSTNode find(String key)
{
 if (t == null)
 return null;
if (key == t.data)
 return t;
if (comp.compare(key, t.data)<0)
return find(key);
else
    return find(key);
}
public void getText(JTextField t, String key)
{
t.setText(key);
}
public String toString()
{
String fail= "The object was not found.";  
return fail;}
}

In particular I'm getting a null pointer exception on line 33 (if (comp.compare(temp.data, newData)<0)).

Any idea why this is happening? Help would be much appreciated!