Grabbing multiple string inputs from System.in using Scanner

Question

My problem is related to grabbing multiple user input strings using Scanner on System.in to retrieve a username/password tuple and store the tuple in a String array.

similar inquiry: Reading multiple Scanner inputs

However, they don't use try/catch and their code seems to work.

When running my code, I get a java.util.NoSuchElementException pointing towards the line : login[1] = input.nextLine();

public void getPassword() throws Exception {
        /* Create a string array to hold username and password */
        String[] login = {"a", "b"};
        System.out.println("Username:\n");
        try (Scanner input = new Scanner(System.in)) {
            login[0] = input.nextLine();
        } catch (NoSuchElementException e) {
            e.printStackTrace();
        }
        System.out.println("Password:\n");
        try (Scanner input = new Scanner(System.in)) {
            login[1] = input.nextLine();
        } catch (NoSuchElementException e) {
            e.printStackTrace();
        }
        System.out.println("username: " + login[0] + "\npassword: " + login[1]);
    }

What could be the problem?

Don't create a Scanner every time you want to read input. Create it once. — Jeremy
– Jeremy, Commented Mar 5, 2017 at 1:40
Should I remove the second try and catch and just put all of it in one block? — Mir
– Mir, Commented Mar 5, 2017 at 1:41
also, use hasNextLine(). that should prevent your exception but the way you're using the scanners is not the proper way. — Ousmane D.
– Ousmane D., Commented Mar 5, 2017 at 1:41
I read many things about not using multiple wrappers for input stream. However, I'm new to java and my tutorial always uses this weird try/catch thing when opening a new scanner object. Would it be better to put everything into one block? — Mir
– Mir, Commented Mar 5, 2017 at 1:44

Jeremy · Accepted Answer · 2017-03-05 01:47:29Z

0

You don't need to catch NoSuchElementException if you first use one of the has*() methods.

For example, the following code will echo the two inputs to the console.

Scanner scan = new Scanner(System.in);
if (scan.hasNextLine()) {
    System.out.println(scan.nextLine());
}
if (scan.hasNextLine()) {
    System.out.println(scan.nextLine());
}

answered Mar 5, 2017 at 1:47

Jeremy

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1 Comment

Mir Over a year ago

Thanks! This did it for me. I removed the try/catch block and the "throws Exception" and replaced with similar lines above. I did not understand the use of the hasNextLine() method but I looked up documentation and now it is clear. Thank you!

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