Trouble reading data from a CSV file

Question

I'm attempting to read data from a CSV file, then put each row into an object, then place the object inside an arraylists of objects. I seem to be getting an error on this line

int age = fileReader.nextInt();

Here is my full code

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package testfileio;

import java.io.FileNotFoundException;
import java.io.File;
import java.util.Scanner;
/**
 *
 * @author gregf
 */
public class TestFIleIO {

    /**
     * @param args the command line arguments
     * @throws java.io.FileNotFoundException
     */
    public static void main(String[] args) 
            throws FileNotFoundException {
        Company jam = new Company();

        File csv = new File("C:\\Users\\gregf\\Documents\\NetBeansProjects\\TestFIleIO\\employees.csv");
        Scanner fileReader = new Scanner(csv);

        fileReader.useDelimiter(",|\n");
        //skips first row (column headers)
        fileReader.nextLine();

        while(fileReader.hasNext()) {
            String name = fileReader.next();
            int age = fileReader.nextInt();
            fileReader.nextLine();

            try {
                jam.setEmployees(new Employee(name, age));
            }
            catch(Exception ex) {
                System.out.println(ex);
            }
        }

        System.out.println(jam);
    }

}

Error

Exception in thread "main" java.util.InputMismatchException
    at java.base/java.util.Scanner.throwFor(Scanner.java:939)
    at java.base/java.util.Scanner.next(Scanner.java:1594)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2258)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
    at testfileio.TestFIleIO.main(TestFIleIO.java:50)
C:\Users\gregf\Documents\NetBeansProjects\TestFIleIO\nbproject\build-impl.xml:1328: The following error occurred while executing this line:
C:\Users\gregf\Documents\NetBeansProjects\TestFIleIO\nbproject\build-impl.xml:948: Java returned: 1
BUILD FAILED (total time: 0 seconds)

A few notes:

Employee is an object with the name: String and age: int data fields

Company is an object that contains an ArrayList of Employee type and has a toString method to print all the employees' names and ages.

Since I have to use this in a project, so I can't use any libraries.

If you have any idea how to solve this, please share, thanks a lot.

InputMismatchException clearly states you migh have non-integer data in the CSV. It may not be strings only- it can be additional spaces or special characters. Use a CSV library for such things. I would say , Scanner is not the tool for this! — Kris, Jul 23 '19 at 07:00
Are you sure that in the CSV file the age is printed as an int? If your value is either a string or maybe a float value or any other type that is strictly not an integer then you get that exception. — Saeleas, Jul 23 '19 at 07:04
Also CSV files that go strictly by the spec use CRLF as a line end, you could be getting CR mixed up in your data if you only use LF. — markspace, Jul 23 '19 at 07:09
https://stackoverflow.com/questions/13879967/good-and-effective-csv-tsv-reader-for-java/27087060 — Ng Sharma, Jul 23 '19 at 07:35
@Kris as I mentioned, since I will have to use this for a project, so I can't use any libraries, but thanks for the input — Michael Jürgengen-Engl, Jul 23 '19 at 08:07

score 1 · Answer 1 · answered Jul 23 '19 at 07:29

Likely you have an input that has some unexpected characters that cannot be parsed as an integer. These may be regular printable characters, or these may be unprintable characters.

Examine your input data. Let your app report the offending data. Retrieve a string rather than an integer. Then attempt to parse using the Integer class. Add a try-catch to trap for parsing error. On error, report the length and content of the offending string.

Tip: Use a library to help with reading/writing CSV. I like Apache Commons CSV, but there are others to choose from as well.

score 0 · Answer 2 · answered Aug 14 '19 at 11:21

It is likely that you are reading in some special characters, I ran into that a fair amount as well so i developed a little module and co-module to read in csv file lines right here:

static Vector<String> specialLine(String input) {
    Vector<String> returner = new Vector<String>();
    int index1=0, index2=0;
    int indexq=input.indexOf('"'), indexc=input.indexOf(',');
    boolean quote = true;
    while(indexq!=-1||indexc!=-1){
        if((indexq>indexc||indexq==-1)&&indexc!=-1) {
            index2=indexc;
            quote=false;
        }else {
            index2=indexq;
            quote=true;
        }
        if(!quote) {
            returner.add(input.substring(index1,index2));
            input = input.substring(index2+1,input.length());
            index1=0;
        }else {
            String[] temp = read_through(input);
            index1=0;
            returner.add(temp[0]);
            input = temp[1];
        }
        indexq=input.indexOf('"');
        indexc=input.indexOf(',');
        quote=false;
    }
    if(quote==false) {
        returner.add(input);
    }
    return returner;
}
static String[] read_through(String input) {
    String[] returner = new String[2];
    boolean stillIn = true;
    int steppy=0, quoteCount=0;
    while(stillIn&&steppy<input.length()) {
        steppy++;
        quoteCount=0;
        while(steppy<input.length()&&input.charAt(steppy)=='\"') {
            quoteCount++;
            steppy++;
        }
        if(quoteCount%2==1) {
            stillIn=false;
        }
    }
    if(steppy>=input.length())
        steppy=input.length()+1;
    returner[0] = String.format("\"%s\"", input.substring(1,steppy-1));
    if(steppy+1>input.length())
        steppy=input.length()-1;
    returner[1] = input.substring(steppy+1,input.length());
    return returner;
}

It mainly takes advantage of the fact hat all special characters are inside double quoted cells and all double quotes have an adjacent double quote, so the escape and entrance sequences are to find an odd number of double quotes in a row.

Trouble reading data from a CSV file

2 Answers2