type of hashtable...

I want to create a hash table having following schema:

for a given tableSize, it creates array of Object class of length tableSize. Every Object in array is actually Vector, to implement binary tree.

here is sample code:

publicstaticclass Roomextends Object{

Vector _node =new Vector();//every room contains a vector, for binary tree implementation

public Room(){

}

publicint insert(int element){

int index=0;

//code here

return index;

}

//gets and sets here...

}

Here how i create this array:

int tableSize = 7;

Room[] hashTable=new Room[tableSize];

int nodeNumber = hashTable[integerToInsert%tableSize].insert(integerToInsert);

Problem is, the last line gives NullPointerException :(

What am I doing wrong? I feel a stupid mistake...

[1576 byte] By [DaniLa] at [2007-11-27 1:49:02]