Error java.lang.NumberFormatException: For input string: ""

Question

I'm trying to read this file

C101

VEHICLE
NUMBER     CAPACITY
  25         200

CUSTOMER
CUST NO.  XCOORD.   YCOORD.    DEMAND   READY TIME  DUE DATE   SERVICE   TIME

    0      40         50          0          0       1236          0   
    1      45         68         10        912        967         90   
    2      45         70         30        825        870         90   
    3      42         66         10         65        146         90   
    4      42         68         10        727        782         90   
    5      42         65         10         15         67         90   
    6      40         69         20        621        702         90   
    7      40         66         20        170        225         90   
    8      38         68         20        255        324         90   

But when I read the file, the program throws me this exception:

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 VRP.main(VRP.java:43)
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

I cheked my code and debugged, but I can't find the problem.

I used an array to save all the spaces between the columns (I only read the first four columns) and then an ArrayList but it doesn't worked.

    public static void main(String[] args) throws Exception {

    File f = new File("C101.txt");
    FileReader fr = new FileReader(f);
    BufferedReader reader = new BufferedReader(fr);

    String nada = reader.readLine();  //C101
    nada = reader.readLine();         //espacio en blanco
    nada = reader.readLine();         //vehicle=25
    nada = reader.readLine();         //number, capacity
    nada = reader.readLine();         //25, 200
    nada = reader.readLine();         //espacio en blanco
    nada = reader.readLine();         //customer
    nada = reader.readLine();         //encabezados
    nada = reader.readLine();         //espacio en blanco

    String[] espacios;
    int capacity = 200;
    int custno, xcoord, ycoord, demand;

    ArrayList<String> guardar = new ArrayList<String>();

    while (reader.ready()) {
        espacios = reader.readLine().trim().split(" ");
        for (int i = 0; i < espacios.length; i++) {
            guardar.add(espacios[i]);
        }
        custno = Integer.parseInt(espacios[0]);
        xcoord = Integer.parseInt(espacios[1]);
        ycoord = Integer.parseInt(espacios[2]);
        demand = Integer.parseInt(espacios[3]);
    }
}

Sorry for the inconvenient and thank you for your time.

Solution 1

You're splitting on a single space but there is more than one space between the integer columns

espacios = reader.readLine().trim().split("\\s+");

Solution 2

You got to make sure that espacios[0] through espacios[3] are actually integers. What you should probably do is print them out to check. If one of them isn't an integer, Integer.parseInt() will throw that exception.

Comments

[ArCiGo]

But all the numbers are Integers

[Hovercraft Full Of Eels]

@ArCiGo: you've got to either use a debgger or println anything. Throw all assumptions out the window. 1+ to the answer.

[ArCiGo]

I found the mistake: at the end of the .txt file a blank space was left by the author

[Reimeus]

It's likely that that this fixed the problem but that the extraneous line at the end of the file caused the same problem later while reading the file