reading and printing from txt file integers java

Question

I wrote the below code in order to read some integers from a text file and then print in a new txt every integer after I added the value ten to each of them. The "-1" int is as a pointer to show the end.

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintWriter;
import java.util.Scanner;

public class SmallChallengeCh {
    public static void main(String[] args){
        Scanner in = null;
        PrintWriter pw = null;
        try{
            File f = new File("C:\\Users\\paioa\\primlnl.txt");
            in  = new Scanner(f);
            pw = new PrintWriter(new FileOutputStream("C:\\Users\\paioa\\primOut.txt"),true);

            int num = in.nextInt();
            while(num != -1 ){
                num = num + 10;
                System.out.print(num + " ");
                pw.print(num + " ");
                num = in.nextInt();
            }
        }catch(FileNotFoundException e1){
            System.out.println("The file does not exist");
        }finally {
            try{
                if(in != null) in.close(); else throw new Exception("NULL");
                if(pw != null) pw.close();else throw new Exception("NULL");
            }catch (Exception e){
                System.out.println(e.getMessage());
            }
        }
    }
}

However I am getting the below error

**Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:864)
    at java.util.Scanner.next(Scanner.java:1485)
    at java.util.Scanner.nextInt(Scanner.java:2117)
    at java.util.Scanner.nextInt(Scanner.java:2076)
    at gr.aueb.elearn.ch6.SmallChallengeCh.main(SmallChallengeCh.java:18)
Process finished with exit code 1**

But I cannot understand why. The inputmismatchexception is due to the fact that probably my file doesn't contain ints but that's not true here is the txt.

Input of txt file, also saved with coding UTF-8

Solved

ANSWER: The issue was with coding UTF-8. I should left the file ANSI. I don't know why the example I was reading/exercising on advocated this ..

at which number does it fail? or, how many numbers have been printed before the error? — UninformedUser, Dec 15 '18 at 20:01
this code is working fine for me without any issues output `19 18 20 ` — Ryuzaki L, Dec 15 '18 at 20:07
I just ran this code against your input and it works fine. Please [edit] your question with more information on how to reproduce your problem. — Joe C, Dec 15 '18 at 20:08
@AKSW it does not print any number in the console. Just creates a blank primOut.txt on the path i have give on my code. — Panagiotis Ioannidis, Dec 16 '18 at 10:03

score 0 · Answer 1 · edited Dec 31 '18 at 12:25

0

try this

int num;
while(in.hasNextInt()){
    num = in.nextInt();
    num = num + 10;
    System.out.print(num + " ");
    pw.print(num + " ");
}

If you want to read only integers before "-1" you have to do something like

int num;
while(in.hasNextInt()){
    num = in.nextInt();
    if(num == -1)
        break;
    num = num + 10;
    System.out.print(num + " ");
    pw.print(num + " ");
}

edited Dec 31 '18 at 12:25

Wojciech Wirzbicki

3,887
6
36
59

answered Dec 15 '18 at 22:00

paola_in_wonderland

1
2

reading and printing from txt file integers java

Solved

1 Answers1