NumberFormatException parseInt Java

Question

I am trying to differentiate and store data (Point: x, y) from a text file in two arraylists: knots and zeros. Data File just contains integers or decimal values.

Data File:
x    y  type(zero/knot) 
46  10      2
13  5       2
27  21      1

But my code is throwing NumberFormatException:48

import java.util.*;
import java.util.ArrayList;
import java.io.*;
import java.awt.Point;

public class program {

    public static void main(String []args)  {
        ArrayList knots = new ArrayList<Point>();
        ArrayList zeros = new ArrayList<Point>();
        List<Integer> list = new ArrayList<Integer>();
        String line = null;
        String file = "data1.txt";
        BufferedReader reader;
        try  {
            reader = new BufferedReader(new FileReader(file));
            while((line = reader.readLine()) != null)  {
                String tmp[] = line.split(" ");
                System.out.println(line);
                for (String s:tmp) {
                    s = s.replace("\r\n","");
                    int i = Integer.parseInt(s.trim());
                    //knots.add(new Point();
                System.out.println(s);
              }
            }
        }

        catch (FileNotFoundException e)  {
            e.printStackTrace();
        } catch (IOException e)  {
            e.printStackTrace();
        }
            }
        }

so the line "x y type(zero/knot) " isn't actually in the file? — androiddev19
– androiddev19, Commented Sep 3, 2013 at 4:00

MadProgrammer · Accepted Answer · 2013-09-03 04:08:12Z

Assuming the file contents is EXACTLY...

46  10      2
13  5       2
27  21      1

When I run you code, I get the output...

46  10      2
46
Exception in thread "main" java.lang.NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
    at java.lang.Integer.parseInt(Integer.java:504)
    at java.lang.Integer.parseInt(Integer.java:527)
    at testparser.TestParser.main(TestParser.java:47)

This would seem to indicate that there are blank/empty Strings in the output...

If I replace this section...

for (String s : tmp) {
    s = s.replace("\r\n", "");
    int i = Integer.parseInt(s.trim());
    //knots.add(new Point();
    System.out.println(s);
}

With...

for (String s : tmp) {
    s = s.trim();
    if (s.length() > 0) {
        int i = Integer.parseInt(s.trim());
        //knots.add(new Point();
        System.out.println(s);
    }
}

I get...

46  10      2
46
10
2
13  5       2
13
5
2
27  21      1
27
21
1

Don't forget, readline will not return the line terminator, so you should be able to ignore it.

line.split(" ") is spliting on each "individual" space, meaning that if you have more than one space character together, then it will return the second space...;)

If, instead, you use String tmp[] = line.split("\\s+");, it will split on any spaces between all the other characters...not returning any "blank" Strings (making the if (s.length() > 0) { check redundant)

Vimal Bera · Accepted Answer · 2013-09-03 04:08:47Z

1

The problem is in your split line. It should be like this String a[]=s.split(" +"); What happened in your case is : When it split "46 10 2" string with " ", it counts only one space for spliting the String. So it ignores one space after 46 and 10 and then looks for the String. But there is no string after one space so it takes "" as a string and try to parse it in integer. Though "" can't be parsed into integer,it throws NumberFormatException

answered Sep 3, 2013 at 4:08

Vimal Bera

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Comments

Kon · Accepted Answer · 2013-09-03 04:00:02Z

0

You said you are parsing decimal numbers as well. Those cannot be parsed with Integer.parseInt(). You need to use Double.parseDouble() or Float.parseFloat() to parse decimal values from a String.

Also, it looks like you are trying to parse your header in your file. Make sure to do a token readLine() call before you begin the reading of the data, otherwise you'll try to parse text and that makes no sense and will crash.

answered Sep 3, 2013 at 4:00

Kon

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3 Comments

user2398101 Over a year ago

Right now, I am just trying to do integer values, I have two separate data files.

Kon Over a year ago

Then the advice in my second paragraph likely applies, but it will be important to know about parsing floating point values for when you read the other file.

user2398101 Over a year ago

"x y type" is just for illustration, it is not there in the actual file.

NSM · Accepted Answer · 2013-09-03 10:59:24Z

You can try this code.. It works fine for me

import java.util.ArrayList;
import java.io.*;
import java.awt.Point;

public class program 
{
    public static void main(String []args)  
    {
        ArrayList knots = new ArrayList<Point>();
        ArrayList zeros = new ArrayList<Point>();
        List<Integer> list = new ArrayList<Integer>();
        String line = null;
        String file = "data1.txt";
        BufferedReader reader;
        try
        {
            reader = new BufferedReader(new FileReader(file));
            while((line = reader.readLine()) != null) 
            {
                String tmp[] = line.split(" ");
                System.out.println(line);
                for (String s:tmp) 
                {   
                    if(! (s.isEmpty()) )
                    {
                        int i = Integer.parseInt(s.trim());
                        System.out.println(s);
                    }
                }
            }
        }
        catch (FileNotFoundException e)  
        {
            e.printStackTrace();
        }
        catch (IOException e) 
        {
            e.printStackTrace();
        }
    }
}

I hope this will help you.

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