NumberFormatException: null

[S. Shin]

I'm trying to write a program to perform some of the some of the functionality of StringTokenizer for an assignment, my instructor provides the driver and I do the rest. I've gone about as far as I can but I keep hitting a "NumberFormatException: null" run time error when trying to run the driver. I did some digging around and it looks like it's a result of my trying to parse a null value, but I've been banging my head on my desk trying to figure out how to fix it. Here's my code:

Driver (provided):

import java.io.*;
public class Meo04tokenizerDvr
{
  public static void main(String[] args) throws IOException
  {
    FileReader     diskfile = new FileReader("stuMst1.txt");
    BufferedReader inFile   = new BufferedReader(diskfile);
    Meo04tokenizer tok;
    int       n = 0;
    int       tokCt;
    String    rec;
    String    id;
    char      gender;
    String    fname;
    String    lname;
    int       hrs;
    double    gpa;
    String    major;
    String    status;
    String    revName;
    System.out.println();
    System.out.println("Rec Tok Ct  ID  Name              Hrs    GPA  Major Gender   Status");
    System.out.println("--- ------ ---- ----------------- ---    ---- ----- ------ ----------");

    while( (rec = inFile.readLine()) != null)
      {
        tok    = new Meo04tokenizer(rec,',');
        tokCt  = tok.getCount();
        id     = tok.getStrTok();
        gender = tok.getCharTok();
        fname  = tok.getStrTok();
        lname  = tok.getStrTok();
        hrs    = tok.getIntTok();
        gpa    = tok.getDblTok();
        major  = tok.getStrTok();

        if(tok.hasMore())
          status = tok.getStrTok();
        else
          status = "";

        revName = lname + ", " + fname;

        n++;
        System.out.printf("%3d %4d %6s %-16s %4d %7.2f %5s %-6s %s\n",
                      n,tokCt,id,revName,hrs,gpa,major,gender=='f'?"Female":"Male",status);
      }
    System.out.println();
    inFile.close();
  }
}

Here's my program (original):

public class Meo04tokenizer
{
  private String list[] = new String[1000];
  private String svar;
  private int    pos;

  static int currToken  = 0;
  static int ct         = 0;
  //--------------------------------------------------------------------------------------
  public Meo04tokenizer(String rec, char dlm)
  {

    while(rec.indexOf(dlm) >= 0)
    {
      pos = rec.indexOf(dlm);
      list[currToken] = rec.substring (0, pos);
      ct++;
      currToken++;
      rec = rec.substring(pos + 1);
    }

    list[currToken] = rec;
    ct++;
    currToken = 0;
  }
  //--------------------------------------------------------------------------------------
  public String getStrTok()
  {
    currToken ++;
    ct --;
    return list[currToken - 1];
  }
  //--------------------------------------------------------------------------------------
  public int getIntTok()
  {
    currToken ++;
    ct --;
    return Integer.parseInt(list[currToken - 1]);
  }
  //--------------------------------------------------------------------------------------
  public double getDblTok()
  {
    currToken ++;
    ct --;
    return Double.parseDouble(list[currToken - 1]);
  }
  //--------------------------------------------------------------------------------------
  public static char getCharTok()
  {
    char cvar = 'f';

    currToken ++;
    ct --;
    return cvar;
  }
  //--------------------------------------------------------------------------------------
  public static int getCount()
  {
    return ct;
  }
  //--------------------------------------------------------------------------------------
  public static boolean hasMore()
  {
    if(ct > 0)
      return true;

    else return false;
  }
  //--------------------------------------------------------------------------------------
}

Here's the text file it's reading:

1111,f,Anna,Arcello,10,1.01,1040,Suspension
2222,f,Barbara,Brew,20,2.02,1041
3333,f,Cindy,Crawford,30,3.03,1042
4444,f,Debbie,Desoni,40,1.40,1043,Probation
5555,m,Ed,Evans,50,2.50,1045
6666,f,Fonda,Farley,60,3.60,1040
7777,m,George,Goodin,70,1.07,1041,Probation
8888,f,Hedi,Hust,80,2.08,1042
9999,m,Ivan,Ingraham,90,3.09,1044

Here's the error I'm getting:

---------- Capture Output ----------
> "F:\Program Files\Java\jdk1.6.0_07\bin\java.exe" Meo04tokenizerDvr

Rec Tok Ct ID Name Hrs GPA Major Gender Status
--- ------ ---- ----------------- --- ---- ----- ------ ----------
1 8 1111 Arcello, Anna 10 1.01 1040 Female Suspension
Exception in thread "main" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Integer.java:415)
at java.lang.Integer.parseInt(Integer.java:497)
at Meo04tokenizer.getIntTok(Meo04tokenizer.java:45)
at Meo04tokenizerDvr.main(Meo04tokenizerDvr.java:46)
> Terminated with exit code 1.

I'd really appreciate any help you guys can give me.

[Jesper de Jong]

Look carefully at the stack trace. Especially this line:

at Meo04tokenizer.getIntTok(Meo04tokenizer.java:45)

It tells you exactly where in your source code the error happened.

In that line of code, you are parsing an object into a number, but the thing you are trying to parse is null. That's not a valid input for Double.parseDouble(...), so you get a NumberFormatException. Lookup the method Double.parseDouble(...) in the Java API documentation.

[Paul Yule]

The problem is the huge list of tokens that you place each line in that I think is muddling up your ability to debug. We could have a reasonable discussion about they way this is being done but the long and short of your problem is when you create the constructor for the tokenizer the indexes for the list should begin anew. Since your list object isn't static it's being recreated every time you create the object so you aren't keeping every line in there anyway. Since the indexes are static among each one of those objects you keep the indexes you were at before but you don't even have the old line there.

currToken =0;

At the beginning of your Meo04tokenizer constructor should fix your issue.

[S. Shin]

Paul Yule wrote:The problem is the huge list of tokens that you place each line in that I think is muddling up your ability to debug. We could have a reasonable discussion about they way this is being done but the long and short of your problem is when you create the constructor for the tokenizer the indexes for the list should begin anew. Since your list object isn't static it's being recreated every time you create the object so you aren't keeping every line in there anyway. Since the indexes are static among each one of those objects you keep the indexes you were at before but you don't even have the old line there.

currToken =0;

At the beginning of your Meo04tokenizer constructor should fix your issue.

Worked perfect, thanks a ton! I'll look over the way things are laid out and try to make them a bit more efficient.

[Paul Yule]

Glad to help.