Error when reading from text file

Question

I keep getting this error when reading from a text file it gets the first few numbers but then does this there also shouldnt be 0's in there, tried a lot of things not sure what to do. I have to be able to read the file numbers and then multiply specific ones could use some help thanks. (I was using the final println to check what numbers it was getting). Sorry forgot the error is this output 4 32 0 38 0 38 0 16 0 Error: For input string: ""

Here is my file:

Unit One
4
32 8
38 6
38 6
16 7

Unit Two
0

Unit Three
2
36 7
36 7

Unit Four
6
32 6.5
32 6.5
36 6.5
36 6.5
38 6.5
38 6.5

Unit Five
4
32 6.5
32 8
32 7
32 8

Unit Six
5
38 7
30 6.5
24 8
24 8
24 8

Unit Seven
0

Unit Eight
1
40 12

Unit Nine
5
24 8
24 6.5
30 6.5
24 7
32 7

And here is my code:

package question;

import java.io.*;
import java.util.Scanner;


public class Weight
{
    

    
        public static void main(String[] args)//main method
        {
            try
            {
                
                Scanner input = new Scanner(System.in);
                //System.out.print("Please enter proposed weight of stock : ");
                // int proposedWeight = input.nextInt();
                
                File file = new File("MathUnits.txt");
                System.out.println(file.getCanonicalPath());
                FileInputStream ft = new FileInputStream(file);

                DataInputStream in = new DataInputStream(ft);
                BufferedReader br = new BufferedReader(new InputStreamReader(in));
                String strline;

                while((strline = br.readLine()) != null)
                {   int i = 0;
                    if (strline.contains("Unit"))
                    {
                        continue;
                    }
                    else {
                String[] numstrs = strline.split("\\s+"); // split by white space
                int[] nums = new int[numstrs.length];
                nums[i] = Integer.parseInt(numstrs[i]);
                
                     for(int f = 0; f <numstrs.length; f++)
                     {
                    System.out.println(""+ nums[f]);
                     }
                    }
                    i ++;
                }
                //int x = Integer.parseInt(numstrs[0]);
               // int m = Integer.parseInt(numstrs[1]);
               // int b = Integer.parseInt(numstrs[2]);
               // int a = Integer.parseInt(numstrs[3]);
                  int a = 0;
                //   System.out.println("this >>" + x + "," + m +"," + b + "," + a);
                   
                //   if(proposedWeight < a)
                 //   {
                //       System.out.println("Stock is lighter than proposed and can hold easily"); 
                 //       System.exit(0);

                       
                //    }
                //    else if ( a == proposedWeight)
                //    { 
                        
                    //  System.out.println("Stock is equal to max");   
                    //  System.exit(0);
                  //  }
                  // else
                  // {
                    //   System.out.println("stock is too heavy");
                    //   System.exit(0);

                      
                 //  }
                   
                
                
        
                
                in.close();
            }
            catch(Exception e)
            {
                System.err.println("Error: " + e.getMessage());
            }
            
            
            }
            

        }

added the error now i forgot to add it in it is this > 4 32 0 38 0 38 0 16 0 Error: For input string: "" it shouldnt have the 0's and the input string error also — user3043724
– user3043724, Commented Nov 27, 2013 at 23:28

FuriKuri · Accepted Answer · 2013-11-27 23:08:36Z

1

One probable error I see

You're not taking newlines into consideration, especially when you're doing a nums[i] = Integer.parseInt(numstrs[i]); on an empty string

Also, I don't think you're getting the numbers into the array correct since you're getting only one int from each line, when some lines have two

answered Nov 27, 2013 at 23:08

FuriKuri

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9 Comments

user3043724 Over a year ago

do u know what the best way to take the empty line into consideration would be? Whats the best way to fix the array?

FuriKuri Over a year ago

Add an if statement to check for a new line and for the array, you have the right idea in the code, check your nums[i] = Integer.parseInt(numstrs[i]); and ask yourself, how many times will it run when you read one line? and how many times would you need it to run, look in the two lines above it (you'd prob just need a for loop)

user3043724 Over a year ago

ok i think I understand that part any idea why im getting the 0's in there?

FuriKuri Over a year ago

it goes back to the not adding numbers into your array correctly, if you made an array of size 2, it defaults the values to zero. So if you only added one int from your line into the array, the other value in the array would still be zero because you never added the second value into it.

FuriKuri Over a year ago

your output " 4 32 0 38 0 38 0 16 0" notice how the second value is never outputted correctly

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