java homework errors

[d4n0wnz]

my assignment is to write a 2 functions that check how many elements are in a linked list
one of the functions have to solve it recursively and the other through the use of a loop.
When compiling my code, I run into a load of errors and can't seem to correct them, which I guess is because of my poor knowledge of java syntax.

So.. heres my code:

public class hmwrk2   
{
 public class lp
{
  public int first;
  public lp rest;
  public lp list1;  
  public lp(int first1, lp rest1)
  {
    first = first1;
    rest = rest1;
  }
}
//15
        public static void count_list(lp list1)
        {int count = 0;
         while (list1 != null)   
         {count++;}
         return count;
        }
//22
        public static void rCount_list(lp list1)
        {
         if(list1.first == 0)
         {return 0;}
         else return rCount_list(list1.rest) + 1;
        }
//29
        public static void main(String[]args)
        {list1 = new lp(1, new lp(2, new lp(3, null)));
         int num = count_list(list1);
         int num1 = rCount_list(list1);
         System.out.println("length computed with a loop: " + num);
         System.out.println("length computed with recursion: " + num1);
         
        }
}

The errors from my compiler:

hmwrk2.java:20: cannot return a value from method whose result type is void
return count;
^
hmwrk2.java:26: cannot return a value from method whose result type is void
{return 0;}
^
hmwrk2.java:27: cannot return a value from method whose result type is void
else return rCount_list(list1.rest) + 1;
^
hmwrk2.java:31: cannot find symbol
symbol : variable list1
location: class hmwrk2
{list1 = new lp(1, new lp(2, new lp(3, null)));
^
hmwrk2.java:31: non-static variable this cannot be referenced from a static context
{list1 = new lp(1, new lp(2, new lp(3, null)));
^
hmwrk2.java:31: non-static variable this cannot be referenced from a static context
{list1 = new lp(1, new lp(2, new lp(3, null)));
^
hmwrk2.java:31: non-static variable this cannot be referenced from a static context
{list1 = new lp(1, new lp(2, new lp(3, null)));
^
hmwrk2.java:32: cannot find symbol
symbol : variable list1
location: class hmwrk2
int num = count_list(list1);
^
hmwrk2.java:33: cannot find symbol
symbol : variable list1
location: class hmwrk2
int num1 = rCount_list(list1);
^
9 errors

I have been playing around with the syntax for an hr and am a bit stuck

[VernonDozier]

public class hmwrk2   
{
 public class lp
{
  public int first;
  public lp rest;
  public lp list1;  
  public lp(int first1, lp rest1)
  {
    first = first1;
    rest = rest1;
  }
}
//15
        public static void count_list(lp list1)
        {int count = 0;
         while (list1 != null)   
         {count++;}
         return count;
        }
//22
        public static void rCount_list(lp list1)
        {
         if(list1.first == 0)
         {return 0;}
         else return rCount_list(list1.rest) + 1;
        }
//29
        public static void main(String[]args)
        {list1 = new lp(1, new lp(2, new lp(3, null)));
         int num = count_list(list1);
         int num1 = rCount_list(list1);
         System.out.println("length computed with a loop: " + num);
         System.out.println("length computed with recursion: " + num1);
         
        }
}

The "cannot return a value" errors are the easiest. If you make a function a void function, it can't return a value. That's the definition of a void function. It doesn't return a value. If you want the function to return an int, change the word "void" to "int" in the function declaration.

Currently your lp class ends at line 14 above. The functions starting after line 15 are NOT in your lp class. Do you want them to be? If so, move the end bracket on line 14 lower to include the functions that you want to have in that class. In lines 31, 32, 33, you refer to list1, which is part of the lp class. Since main isn't in lp, it doesn't know you are referring to the lp class, so that's that error. I'd actually name the variable in lines 31 through 33 something different from list1 here since having the variable name be the same be the same as a data member can be quite confusing.

I fixed the static error and tried to run the program and got into an infinite loop in lines 18 - 20 due to the fact that list1 never changes in those lines so once in the while loop, you never get out.