Write two functions to find the the number of elements in a linked list?

Question

I am trying to Write two functions to find the the number of elements in a linked list. One method using recursion and One method using a loop...
//The linked List class is Represented here.
public class lp {
public int first;
public lp rest;
public lp(int first1, lp rest1)
first = first1;
rest = rest1;
The program i wrote so far is
import java.util.*;
import linklist.lp;
public class listCount{
//loop function
public static void show_list(lp list)
int counter = 0;
while(list != null)
list = list.rest;
counter++;
System.out.println ("length computed with a loop:" + counter);
//recursive function
public static int recursive_count(lp list)
if (list.first == null)
return 0;
else
return recursive_count(list.rest) + 1;
//main method
public static void main (String args[])
lp list1 = new lp(1, new lp(2, new lp(3, null)));
show_list(list1);
System.out.println("length computed with a recursion:" +
recursive_count(list1));
at the if (list.first == null) line i get the error " incomparable types:
int and <nulltype>" I know this is a beginners error but please
help...What should I do?

Answer 1

byte, char, short, int, long, float, double, and boolean are primitives, not objects. They have no members, you cannot call methods on them, and they cannot be set to or compared with null.