How to read input in an online test in Java - InputMismatchException

Question

I got an InputMismatchException in Java when I tried to read the following input.

Input

1          // Integer
aaa        // String
IND        // String
1.2        // Double

My code was like this:

Scanner in = new Scanner(System.in);

int n = in.nextInt();
String name = in.next();
String place = in.next();
double num = in.nextDouble();

Please tell me how do I handle the consecutive strings. I think it fails there due to some \n (newline) character problem.

Try putting in.next() after next int, if i remember correctly that will take in the newline after the int and discard it. — Patrick, Mar 12 '19 at 18:49
I tried that, but for some reason it didn't fix the problem. — Vaishnavi Killekar, Mar 12 '19 at 18:55
I tried running it in an online compiler and it seemed to work without exception, could you provide the full exception it's giving you — Patrick, Mar 12 '19 at 18:57
How did you do it? I've just shown a sample of my problem here. This didn't work for me. How did you run it? The input is given all at once, like in HackerRank or some similar platform. — Vaishnavi Killekar, Mar 12 '19 at 18:57
are the comments included with the input present in the actual input file? That's the only way I can cause the exception to happen — Patrick, Mar 12 '19 at 18:59
No the comments are not included. I actually wrote that code in a test, so I don't have it right now. — Vaishnavi Killekar, Mar 12 '19 at 19:00

isapir · Answer 1 · 2019-03-12T20:30:33.173

You might have a setting that configures a weird delimiter. You can get the bytes of your delimiter by running:

StringBuilder sb = new StringBuilder();
for (byte b : in.delimiter().toString().getBytes()) {
    sb.append(String.format("%02X ", b));
}
System.out.println(sb);

On my Ubuntu Java 1.8u202 64bit I get:

5C 70 7B 6A 61 76 61 57 68 69 74 65 73 70 61 63 65 7D 2B

If that's the case, you can specify the delimiter explicitly, e.g.

Scanner in = new Scanner(System.in).useDelimiter("\n");

Another thing you can try is the following snippet which hard cods the inputs, and allows to change the delimiter easily for further testing:

public static void main(String[] args) {

    String delim = "\n";
    String[] values = new String[]{ "1", "aaa", "IND", "1.2" };

    Scanner in = new Scanner(String.join(delim, values));

    int n = in.nextInt();
    String name = in.next();
    String place = in.next();
    double num = in.nextDouble();

    System.out.printf("%d\t%s\t%s\t%f\n", n, name, place, num);
}

I'll try this out. Thanks! – Vaishnavi Killekar Mar 12 '19 at 18:59 — Vaishnavi Killekar, Mar 12 '19 at 18:59
@VSK I added some more things you can test – isapir Mar 12 '19 at 20:31 — isapir, Mar 12 '19 at 20:31

score 0 · Answer 2 · answered Mar 12 '19 at 19:11

0

Maybe it is the double that is causing the problem. Try using a comma (1,2) instead of dot(1.2) when you input the values

answered Mar 12 '19 at 19:11

Tony

1
1

That could be the case if the Locale is set to a region that uses `,` for decimal – isapir Mar 12 '19 at 20:33
The input is given automatically. I can't change it. – Vaishnavi Killekar Mar 13 '19 at 05:09

How to read input in an online test in Java - InputMismatchException

2 Answers2