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I have an assignment for school that is going to be tested using a premade textfile that feeds data into the program. My problem is that this premade text file crashes the program, even though it works without a problem when you type the data in manually. I've managed to recreate the problem in a much smaller program:

import java.util.Scanner;
import java.util.ArrayList;

public class DoubleTest {

public static void main(String[] args){

    ArrayList<String> fNames = new ArrayList<>();
    ArrayList<String> sNames = new ArrayList<>();
    ArrayList<Double> scores = new ArrayList<>();
    Scanner keyboard = new Scanner(System.in);
    int i = 1;

    while(i != 0){
        System.out.println("First name (quit by typing 0): ");
        String fName = keyboard.nextLine();
        if(fName.equals("0")){
            i = 0;
        }else{
            System.out.println("Result: ");
            double score = keyboard.nextDouble();
            keyboard.nextLine();
            System.out.println("Last name: ");
            String sName = keyboard.nextLine();
            fNames.add(fName);
            sNames.add(sName);
            scores.add(score);
        }
    }
    for(String s : fNames){
        System.out.println(s);
    }

    for(String s : sNames){
        System.out.println(s);
    }

    for(Double d : scores){
        System.out.println(d);
    }
}
}

Now if I simply write the input as it goes along, everything works fine. But if I use a premade text file that I just copy paste it throws an exception. The program asks for a firstname, then a result (double) and then the last name. Then you can either enter in a new first name or quit by typing 0. This is the textfile

name1
20
name1
30
name2
40
name2
name3
50
name3
name4
60
name4

And this is the exception:

 Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Unknown Source)
    at java.util.Scanner.next(Unknown Source)
    at java.util.Scanner.nextDouble(Unknown Source)
    at DoubleTest.main(DoubleTest.java:21)

Any ideas on how to fix this? And again, it doesn't throw an exception when I type it in manually!

Viggo Gustavii
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  • Can you explain in more detail how you "copy paste" the input? This highly depends on what console type of program you're using to accept the input. It is possible it is taking the whole text as a single line. – James Wierzba Mar 29 '16 at 17:07
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    What prevents you debugging your own code? – Raedwald Mar 29 '16 at 17:28
  • Each iteration of your loop reads three lines of input. What are the fourth, fifth, and sixth lines of your text file? Do they match what your code is trying to read? – VGR Mar 29 '16 at 17:30
  • I'm using Eclipse's own console to do input. Thing is if I only had, say, strings as inputs it wouldnt have a problem with it. String, int, String, String (or whatever) works aswell, it's only the double that throws the exception. – Viggo Gustavii Mar 30 '16 at 15:27
  • I'm still a beginner at this so tbh I wouldn't know what to look for – Viggo Gustavii Mar 30 '16 at 15:28
  • And yes, the program wants a String, then a double and then a String again. So the textfile is correct – Viggo Gustavii Mar 30 '16 at 15:30

0 Answers0