Java userInput Validation

Question

I need help with this part of code i am fairly new at coding so i am not that good below is the question Ask user to input a double(number), if the value entered is not a double it continues asking them until they enter a double. Once they enter a double it checks if the double entered is in the range (between 1-25). It will continue prompting until age1 is in that range.

Scanner input = new Scanner(System.in);

while(!input.hasNextDouble()) 
{
    input.nextLine();
    System.out.print("Input is not a number ReEnter:");
 }
 double age1 = input.nextDouble();
 while (age1 < 1 || age1 > 25)
 {
 System.out.print( "Enter the Age between 1-25 Only!");
       age1 = input.nextDouble();
         }

This may help you

Swapnil Padaya
– Swapnil Padaya

2020-10-10 01:11:14 +00:00
Commented Oct 10, 2020 at 1:11 — Swapnil Padaya
– Swapnil Padaya, Commented Oct 10, 2020 at 1:11

Chad · Accepted Answer · 2020-10-10 14:42:54Z

2

Your code runs just fine. Though it won't check if a valid double is entered after it reaches the second while loop, so it's best you combine the validation in a single loop:

Scanner input = new Scanner(System.in);

        while(true) 
        {
            if(!input.hasNextDouble()) {
                input.nextLine();
                System.out.print("Input is not a number ReEnter:");
            }else {         
                double age1 = input.nextDouble();
                if (age1 < 1 || age1 > 25){
                    System.out.print( "Enter the Age between 1-25 Only!");
                    input.nextLine();
                }else {
                    break;
                }
            }
         }

edited Oct 10, 2020 at 14:42

answered Oct 10, 2020 at 1:46

Chad

614 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Kel Varnsen Over a year ago

I'd replace System.exit(0) with break

Swapnil Padaya · Accepted Answer · 2020-10-10 01:37:06Z

When you need to check range use && cause we need it in between those range
Additionally your condition weak toowhile (age1 < 1 || age1 > 25) it should be
while (age1 >= 1 && age1 <= 25)

Using wrapper class to convert String to double.

            Scanner sc = new Scanner(System.in);
            System.out.print("Enter a double number:");
            String d = sc.next();
            while(true) {
                boolean dot = false;
                for(int i = 0 ; i < d.length() ; i++) {
                    char ch = d.charAt(i);
                    // checking for a decimal 'dot'
                    if(ch == '.') {
                        dot = true;
                        break;
                    }
                }
                if(dot == false) {
                    System.out.print("Input is not a double number ReEnter:");
                    d = sc.next();
                }else {
                    // wrapper class
                    double age = Double.parseDouble(d);
                    if(age >= 1 && age <= 25) {
                        System.out.println("Just prefect");
                        break;
                    }else {
                        System.out.print( "Enter the Age between 1-25 Only!");
                        d = sc.next();
                    }
                }// else block  
            }//while block

Output:

Enter a double number:1
Input is not a double number ReEnter:20
Input is not a double number ReEnter:26.00
Enter the Age between 1-25 Only!15
Input is not a double number ReEnter:15.0
Just prefect

Collectives™ on Stack Overflow

Java userInput Validation

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related