How to get boolean user input using scanner?

Question

So i have to ask the user whether they are above 18 and they have to answer with a true or false. And keep looping until they enter the right input

So far, i have this

boolean b = false;
do {
    try {
        System.out.print("Are you above 18?");
        Scanner n = new Scanner(System.in);
        boolean bn = s.nextBoolean();

        if (bn == true) {
            // do stuff
        } else if (bn == false) {
            // do stuff
        }

    } catch (InputMismatchException e) {
        System.out.println("Invalid input!");
    }
} while (!b);

HOWEVER, it wont work as the loop keeps going and it wont read the input right and do my if statements. How do i fix this? Thanks!

bn == true is redundant. bn evaluates to a boolean value. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented May 15, 2014 at 0:47
Are you setting your b variable to true inside one of your conditions? Your loop won't stop until b is true and it's not reference anywhere in your loop. Did you mean to do while (!bn)?. — Kon
– Kon, Commented May 15, 2014 at 0:47
Just off the topic, replace your if(bn == true) with if(bn). — M-Wajeeh
– M-Wajeeh, Commented May 15, 2014 at 0:48

vkg · Accepted Answer · 2014-05-15 00:51:10Z

5

slight tweak to your program. This works

boolean b = false;
        do {
            try {
                System.out.print("Are you above 18?");
                Scanner n = new Scanner(System.in);
                boolean bn = n.nextBoolean();
                if (bn == true) {
                    System.out.println("Over 18");
                } else if (bn == false) {
                    System.out.println("under 18");
                }

            } catch (InputMismatchException e) {
                System.out.println("Invalid input!");
            }
        } while (!b);

And the output is

Are you above 18?true
Over 18
Are you above 18?false
under 18
Are you above 18?

answered May 15, 2014 at 0:51

vkg

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1 Comment

vkg Over a year ago

Just formatted it. Indentations were little off. :) Not sure if that's what was your question?

Omal Perera · Accepted Answer · 2017-06-13 10:10:50Z

2

You need to re-check your Scanner statement and Initializing statement...

Scanner n = new Scanner(System.in);
boolean bn = s.nextBoolean();

It should be

Scanner n = new Scanner(System.in);
boolean bn = n.nextBoolean();

edited Jun 13, 2017 at 10:10

Omal Perera

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answered Jun 13, 2017 at 8:20

Rajat.r2

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Comments

Code-Apprentice · Accepted Answer · 2014-05-15 00:49:45Z

0

Try changing

boolean bn = s.nextBoolean();

to

b = s.nextBoolean();

answered May 15, 2014 at 0:49

Code-Apprentice

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Comments

Hello World · Accepted Answer · 2014-05-15 00:56:25Z

0

Use-

scanner.nextBoolean()

    do{
      try{
          System.out.print("Are you above 18?");
          Scanner scanner = new Scanner(System.in);
          if(scanner.nextBoolean()==true)
           //do stuff

          }else{

          //do stuff
          }
       }

answered May 15, 2014 at 0:56

Hello World

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