Validating a inputted char variable. Do-while loop will not break

Question

I have a method that checks if the user is a student, but I can't get it validate the conditions.

char custStud = '0';
Scanner input = new Scanner(System.in);

do{
       System.out.println("Are you a student? (Type Y or N): ");
       custStud = input.next().charAt(0);
       custStud = Character.toLowerCase(custStud);
  }
  while (custStud != 'y' || custStud != 'n');

When I fire up this program, it does not break the loop, even if 'y' or 'n' are entered. I suspect custStud might have accidentally changed types when changed to lowercase, but I'm not sure. How can I make this loop work properly?

while (custStud != 'y' || custStud != 'n'); always going to be true — Scary Wombat
– Scary Wombat, Commented Aug 10, 2017 at 6:57
@batPerson what will happen if N is pressed , do loop continue if user input N — mohit sharma
– mohit sharma, Commented Aug 10, 2017 at 7:00
@batPerson Have a look and upvote or accept answer if it helps — mohit sharma
– mohit sharma, Commented Aug 10, 2017 at 7:08

Eran · Accepted Answer · 2017-08-10 06:57:06Z

4

while (custStud != 'y' || custStud != 'n') is always true, since custStud can't be equal to both 'y' and 'n'.

You should change the condition to:

while (custStud != 'y' && custStud != 'n')

answered Aug 10, 2017 at 6:57

Eran

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Comments

mohit sharma · Accepted Answer · 2017-08-10 07:02:37Z

1

You've mistaken here:

 while (custStud != 'y' || custStud != 'n');// wrong 
 while (custStud != 'y' && custStud != 'n');// correct

Try running this code:

        char custStud = '0';
        Scanner input = new Scanner(System.in);

        do{
            System.out.println("Are you a student? (Type Y or N): ");
            custStud = input.next().charAt(0);
            custStud = Character.toLowerCase(custStud);
        }
        while (custStud != 'y' && custStud != 'n');
        System.out.print("\n answer:"+custStud);

answered Aug 10, 2017 at 7:02

mohit sharma

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