Can you have a look at my code please, where am i going wrong?

Question

Compiles fine but i get a nullPointerException
in the setLayerOne() method and the setInputs() method
the error seems to point to the Neuron[][] network
but i thought it should be ok as i initilised the pointer as static
the Neuron class is compiled and contains both these methods.
also, is this bad design to make all my varibles static like this
thanks for the help
Tim
import java.io.*;
public class Guesser {
  static char[] user = new char[100];
  static int guess_no = 1;
  static int noOfLayers;
  static BufferedReader br = new BufferedReader( new InputStreamReader(System.in));
  static Neuron[][] network;
  static int[] layers;
  public static void main(String args[])
    throws IOException
    guesserNetwork();
  ///now for the guessing bit
  int guess_no = 0;
  char guess;
  //char dummy;
  //BufferedReader br = new BufferedReader( new InputStreamReader(System.in));
  char[] user = new char[100];
  while (guess_no<10) {
    System.out.println("Please think of Heads (H) or Tails (T) then press enter.");
    if (guess_no == 1)
      guess = 'H';
    else if ( user[guess_no] == 'H' )
      guess = 'T';
    else
      guess = 'H';
    // now we tell the user what our guess was,
    char dummy;
    dummy = (char) br.read(); // wait for the return key pressed
    System.out.println(guess);
    // Find out what the user was thinking of
    // and force the user to H or T
    user[guess_no] = (char) br.read();
    if (user[guess_no] == 'h')
    {user[guess_no] = 'H';}  //this does not work i dont know why
    else if (user[guess_no] == 't')
    {user[guess_no] = 'T';}
    dummy = (char) br.read(); // clear the stream for the return key press
    while ( user[guess_no] != 'H' && user[guess_no] != 'T')
      System.out.println("You must enter H or T");
      user[guess_no] = (char) br.read();
    setLayerOne();  //////HERES WHERE I GET NULLPOINTER EXCEPTION
    guess_no++;
  while (guess_no<100){
    //call update method
    //print output of last node
    network[0][guess_no].inputGuess(guess_no);
    guess_no++;
  static void setLayerOne() ////I GET NULLPOINTER EXCEPTION
   network[0][guess_no].inputGuess(guess_no); // sets the first layer neurons
  static void setInputs ()
     for (int i = 1; i < noOfLayers; i++){
       for(int j=0; j < layers; j++){
network[i][j].updateInput(i, network[i-1], network[i-1].length); //sets the other neurons
static void guesserNetwork()
int noOfNeurons[] = {10,1,1};
int nodes = 0;
noOfLayers = 3;
int[] layers = new int[noOfLayers];
for (int i =0; i < noOfLayers; i++)
layers[i] = noOfNeurons[i];
System.out.println("layer " + (i + 1) + " has " + noOfNeurons[i] + " neurons");
nodes += noOfNeurons[i];
System.out.println("total no of nodes = " + nodes);
System.out.println("building network...");
//make (noOfLayers)arrays of arrays
Neuron[][] network = new Neuron[noOfLayers][];
for (int i=0; i < noOfLayers; i++)
//for each layer make the desired number of rows(of neurons)
int rows = layers[i];
network[i] = new Neuron[rows];
//instinate neuron objects one by one
for (int j=0; j < layers[i]; j++)
if (i==0)
network[i][j] = new Neuron(noOfLayers, i, j, rows, 1, user[j]);
else
boolean isFirstLayer = false;
network[i][j] = new Neuron(noOfLayers, i, j, rows, layers[i-1], network[i-1]);

Answer 1

Main calls guesserNetwork() which initilises the array:-
Neuron[][] network = new Neuron[noOfLayers][];
     for (int i=0; i < noOfLayers; i++)
       //for each layer make the desired number of rows(of neurons)
       int rows = layers;
network[i] = new Neuron[rows];
//instinate neuron objects one by one
for (int j=0; j < layers[i]; j++)
if (i==0)
network[i][j] = new Neuron(noOfLayers, i, j, rows, 1, user[j]);
else
boolean isFirstLayer = false;
network[i][j] = new Neuron(noOfLayers, i, j, rows, layers[i-1], network[i-1]);
later main calls setLayerOne():-
static void setLayerOne()
   network[0][guess_no].inputGuess(guess_no); // sets the first layer neurons
  }and gives this error:-
NullPointerException:
at Guesser.setLayerOne(Guesser.java:77)
at Guesser.main(Guesser.java:62)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
I nave set network[][] to static so that it can be acessed from the main method and the other methods in this class.
thanks again