Probably very easy question about isNaN() java

  • Java
  • Thread starter BiGyElLoWhAt
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    Java
In summary, the conversation is about an individual experiencing an error while using the method isNaN(String) and attempting to tokenize a text document. The conversation also discusses implementing exception handling and possible solutions for converting strings to numbers. The individual is also working on a program in Java to read a file and create a progress report for students, but is encountering errors. They are seeking help and discussing the use of try blocks and skipping tokens.
  • #1
BiGyElLoWhAt
Gold Member
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this is throwing me an error
while(! isNaN(s.next()))
"The method isNaN(String) is undefined for the type ProgressReport"
s is a scanner.

I'm just trying to tokenize a text doc of the form
int
String int ... int
...
String int ... int
int
String int ... int
...
String int ... int
etc.

Oh yea, the question...
Why? What am I doing, or what do I need to do?
 
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  • #2
isNaN expects a number, not a string. Did you try converting the string the a number first?
 
  • #3
mfb said:
isNaN expects a number, not a string. Did you try converting the string the a number first?

I also assume that the OP isn't trying to check for NaN but is actually wants some sort of IsInteger function like Integer.parseInt() but to that one on his data requires exception handling.
 
Last edited:
  • #4
Yea, I changed how I'm doing it.
Java:
import java.io.*;
import java.util.*;
import java.lang.*;

public class ProgressReport{   
   
    File file = new File("grades.txt");   
    Student[][] student;
    int[] scores;
    String name;
   
   
    public ProgressReport() throws FileNotFoundException{
        readInputFile();
    }
   
   
    private void readInputFile() throws FileNotFoundException{
        Scanner s = new Scanner(file);   
        Scanner line;
        int[] sec = {0,0};
        int k = -1;
        int j = -1;
       
        while(s.hasNextLine())
        {
            String str = s.nextLine();
            k++;
            if(str.length() == 1)
            {
                j++;
                sec[j] = Integer.parseInt(str);
            }
            else{
                line = new Scanner(str);
                while(line.hasNext())
                {
                    try
                    {
                        for(int i =0; ;i++)
                        {   
                            scores[i] = Integer.parseInt(line.next());
                        }
                    }
                    catch(Exception e)
                    {
                        name = line.next();
                    }
                   
                   
                }
                student[j][k] = new Student(name, scores);

               
            }
           
           
        }
    }
}
 
  • #5
Haven't done java in a while, so I might be doing things stupidly.

If I use next() in a try block, is that going to skip that token? So in other words, will this give me a string number for my name value?
 
  • #6
The file I'm working with is:
Section number //single digit
Name Score Score Score Score Score //Student data
Student data
...
Section number
student data
student data
 
  • #7
Hmmm... I'm having some errors. I'm getting the string correctly, but I'm not filling my scores variable, and am crashing everytime I try to create a student.
 

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