Java. Trouble with NullPointerException error when creating the tmpNode. I can't figure out why its Null when I have integer values for the Node. This is the line that errors tmpNode = cardList.newNode(Integer.valueOf(tokens[0]),Integer.valueOf(tokens[1]));

public static void main(String[] args) throws FileNotFoundException { Integer amount; LinkedList cardList = null; Node temp = null; Node tmpNode = null; Integer num1; Integer num2; File file = new File("input.txt"); Scanner input; input = new Scanner(file); amount = input.nextInt(); System.out.println(amount); while(input.hasNextLine()) { String value = input.nextLine(); System.out.println(value); if(value.isEmpty()) continue; String tokens[] = value.split("\\s+"); num1 = Integer.valueOf(tokens[0]); num2 = Integer.valueOf(tokens[1]); System.out.println(num1); System.out.println(num2); System.out.println(tokens[0]); System.out.println(tokens[1]); tmpNode = cardList.newNode(Integer.valueOf(tokens[0]),Integer.valueOf(tokens[1])); System.out.println(tmpNode); //cardList.InsertSortedManner(temp); } //cardList.printList(); input.close(); }

public class LinkedList {

Node headref;

class Node {

int name;

int data;

Node next;

Node(int n, int d) {

name = n;

data = d;

next = null;

}

}

//Method to insert node in Sorted Order

void InsertSortedManner(Node temp) {

Node current;

//Check if head is null or head data is less than new node data

if (headref == null || headref.data <= temp.data) {

temp.next = headref;

headref = temp;

} else {

current = headref;

//Iterate till we reach last node and my new node data is less than curr data

while (current.next != null && current.next.data >= temp.data)

current = current.next;

temp.next = current.next;

current.next = temp;

}

}

//Method that returns NewNode

Node newNode(int n, int data) {

Node x = new Node(n, data);

return x;

}

//Print list method that writes to file output.txt

void printList() {

Node temp = headref;

//buffered writer

BufferedWriter bw = null;

//FileWriter initialised to null

FileWriter fw = null;

try {

//Output will be written in output.txt

fw = new FileWriter("output.txt");

bw = new BufferedWriter(fw);

try{

while (temp != null) {

//Print name in console

System.out.println("Number: " + temp.name);

//Print Priority in console

System.out.println("Cost: " + temp.data);

//Name in file

bw.write("Name: " + temp.name);

bw.write(" ");

//Priority in file

bw.write("Priority: " + temp.data);

bw.write(" ");

temp = temp.next;

}

}catch(InputMismatchException e){

}

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

if (bw != null)

bw.close();

if (fw != null)

fw.close();

} catch (IOException ex) {

ex.printStackTrace();

}

}

} } }