The error I'm getting after inputing 1 line:

C:\Users\Eimhin\College>java Directory
test test 123
Exception in thread "main" java.lang.NullPoin
        at Population.fill(Directory.java:26)
        at Directory.main(Directory.java:76)

The program:

class Person
{
    String forename;
    String surname;
    int number;
    void getPerson()
    {
        forename = Console.readToken();
        surname = Console.readToken();
        number = Console.readInt();
    }
    void putPerson()
    {
        System.out.println(surname + ", " + forename + "\t" + number);
    }
}
class Population
{
    Person[] group = new Person[1000];
    int i = 0;
    void fill()
    {
        while (!Console.endOfFile())
        {

            group[i].getPerson();
            i++;
        }
    }
    void swap(int j, int k)
    {
        Person tmp = new Person();
        tmp = group[k];
        group[k] = group[j];
        group[j] = tmp;
    }
    void sort()
    {
        int j = 0;
        int k = 0;
        int min = 0;
        while(j < i)
        {
            min = j;
            while(k < i)
            {
                if(group[min].surname.equals(group[k].surname))
                {
                    if(group[min].forename.compareTo(group[k].forename) > 0)
                        min = k;
                }
                else if(group[min].surname.compareTo(group[k].surname) > 0)
                    min = k;
                k++;
            }
            swap(j, min);
            j++;
        }
    }
    void display()
    {
        for(int j = 0; j < i; j++)
            group[j].putPerson();
    }
    void sortThenDisplay()
    {
        sort();
        display();
    }
}
class Directory
{
    public static void main(String[] args)
    {
        Population phonebook = new Population();
        phonebook.fill();
        phonebook.sortThenDisplay();
    }
}