Errors trying to read from a .dat file

Question

I am having an error reading a from a .dat file. The .dat file is set up like this:

<Name>/<age>

and I use the / as a delimiter. I am attempting to read from the file to read the name and age, but it comes up with this error:

Exception in thread "main" java.util.InputMismatchException
        at java.util.Scanner.throwFor(Scanner.java:819)
        at java.util.Scanner.next(Scanner.java:1431)
        at java.util.Scanner.nextInt(Scanner.java:2040)
        at java.util.Scanner.nextInt(Scanner.java:2000)
        at Lab04a.input(Lab04a.java:26)
        at Lab04a.main(Lab04a.java:18)
Java Result: 1

The problematic method is this:

public void input() {
        try {
            File dat = new File("Lab04a.dat");
            Scanner sc = new Scanner(dat).useDelimiter("/");
            String name = sc.next();
            int age = sc.nextInt();
            Lab.process(name, age);
        }
        catch(FileNotFoundException e) {
            System.out.println("Missing or corrupted data file.");
            System.exit(0);
        }
    }

The lines giving errors are lines 26 and 18, and these are the lines:

Line 18:

Lab.input();

And line 26:

int age = sc.nextInt();

Line 18 can't have anything wrong, as it only calls the problematic method. Line 26 is (to my best guess) where the error is occurring.

Can you please post up your file content as well? thank you :) — Kick Buttowski, Sep 15 '14 at 19:36
The `Scanner` is looking for an integer after the `/` and the file does not contain any integer. — M A, Sep 15 '14 at 19:38
@manouti when the file content is not clear how we can be sure about it? — Kick Buttowski, Sep 15 '14 at 19:40
@KickButtowski Nevermind. I just based my comment on the content he provided: `/` — M A, Sep 15 '14 at 19:42

score 0 · Answer 1 · answered Sep 15 '14 at 19:39

0

The line

int age = sc.nextInt();

can give you InputMismatchException if the next token does not match the Integer regular expression, or is out of range

answered Sep 15 '14 at 19:39

sol4me

15,233
5
34
34

what is gonna happen if you have ssss/11111 ? – Kick Buttowski Sep 15 '14 at 19:41
Call to sc.next() will print ssss and sc.nextInt() will print 11111 . – sol4me Sep 15 '14 at 19:47
so how do you know your answer will help the op when you donot know about the file content? – Kick Buttowski Sep 15 '14 at 19:48
Because of the fact that there are 2 lines in method input() where scanner is used , next() cannot throw InputMismatchException but nextInt can. – sol4me Sep 15 '14 at 19:50

Davide · Answer 2 · 2014-09-15T19:56:49.193

try this

Scanner sc = new Scanner(dat).useDelimiter("\\/");

EDIT

import java.io.File;
import java.io.FileNotFoundException;
import java.util.*;

/**
 * @author Davide
 */
public class test {
    static Map map;

    public static void main(String[] args) {
        // init value
        input();
    }


    public static void input() {
        try {
            File dat = new File("test.dat");
            Scanner sc = new Scanner(dat).useDelimiter("\\/");
            String name = sc.next();
            int age = sc.nextInt();
            System.out.println(name + " " + age);
        }
        catch(FileNotFoundException e) {
            System.out.println("Missing or corrupted data file.");
            System.exit(0);
        }
    }

}

dat file

ciao/56

UPDATE

try {
    // ...
} catch (InputMismatchException e) {
    sc.next(); 
}

this code does not help the op. you do not know the file content. giving the code answer is not right — Kick Buttowski, Sep 15 '14 at 19:47

Errors trying to read from a .dat file

2 Answers2