CODEWITHSUNDEEP
javavalidation
Q Rice
Q Rice

Reputation: 13

validate integers for certain values in java

I'm trying to verify that users input only 1, 2, or 3. So far I've used sc.hasNextInt() to validate integers, but not those specific ones. Can someone help? My code is below.

System.out.print("Enter Department Number: ");
while (!sc.hasNextInt())                
{
    System.out.println("Invalid entry. Please enter 1, 2, or 3 for the         
                       department number.");
    System.out.print("Enter Department Number: ");                
    sc.next();
}
int department =  (sc.nextInt());

Upvotes: 0

Views: 398

Answers (6)

thegauravmahawar
thegauravmahawar

Reputation: 2823

Your code should be:

System.out.print("Enter Department Number: ");
int department =  sc.nextInt();    
while(department != 1 || department != 2 || department != 3 ) {
  System.out.println("Invalid entry. Please enter 1, 2, or 3 for the         
                       department number.");
  System.out.print("Enter Department Number: ");                
  department = sc.nextInt();
}

Upvotes: 1

Mohammed Aouf Zouag
Mohammed Aouf Zouag

Reputation: 17142

You can proceed like this:

Scanner sc = new Scanner(System.in);
int departement;

do {
   System.out.print("Enter Department Number: ");
   departement = sc.nextInt();
}while (departement != 1 && departement != 2 && departement != 3);

Upvotes: 0

Eugen Hotaj
Eugen Hotaj

Reputation: 383

Not very clean or coherent but

int input;
while(!sc.hasNextInt()||((input=sc.nextInt())>3&&input<1)))

Upvotes: 0

Niels Billen
Niels Billen

Reputation: 2199

Use a while loop where you ask for the next integer and only break when it is inside the correct range:

Code: 

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    int value;
    while (true) {
        System.out.print("Enter Department Number: ");
        if (sc.hasNextInt()) {
            value = sc.nextInt();
            if (value < 1 || value > 3)
                System.out
                        .println("Invalid entry... must be between 1 and 3");
            else
                break;
        }
    }
    else
        sc.next(); // does not block when a string is putted in
    System.out.println(value);
}

Upvotes: 0

Jaroslaw Pawlak
Jaroslaw Pawlak

Reputation: 5588

Read entire line and check that it matches regular expression:

int department;

System.out.print("Enter Department Number: ");
while (sc.hasNextLine()) {
    String line = sc.nextLine();
    if (line.matches("[123]")) {
        System.out.println("Invalid entry. Please enter 1, 2, or 3 for the department number.");
        System.out.print("Enter Department Number: ");
    } else {
        department = Integer.parseInt(line);
        break;
    }
}

Upvotes: 0

andrewdleach
andrewdleach

Reputation: 2466

You do not account for a String-to-Int Conversion or the newLine character left unconsumed.

while (sc.hasNextLine()) {

   int choice = Integer.parseInt(sc.nextLine().trim());
   if (choice == 1 || choice == 2 || choice == 3)
      //do something

}

Upvotes: 1

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