Keep on having StringIndexOutOfBoundsException for this part

Question

I keep getting StringIndexOutOfBoundsException for this part of the code. What could be the reason? contact is declared as String

    do{

        System.out.print("Contact Number (01X-XXXXXXX) :");
        contact = scan.next();
        if(!phNumValidation(contact)){
            System.out.println("Invalid Phone Number. Please try again.");
            System.out.println("");
        }
    }while(!phNumValidation(contact) || contact.length() < 11);

this is the method for phone number validation

public static boolean phNumValidation(String contact){
    boolean valid = true;
    String dash = contact.substring(3, 4);
    if(contact.length() == 11){
        valid = true;
        valid = contact.startsWith("01");
        valid = dash.matches("-");
    }
    else{
        valid = false;
    }

    return valid;
}

What is contact? What is phNumValidation? With this information we cant help you at anything. Please give detailed information. — Sebastian G., Aug 06 '17 at 10:50
Your `substring` is not working on Strings which have lower than 4 characters. — Murat Karagöz, Aug 06 '17 at 10:50
So you're checking whether the fourth character of a string with less than four characters is a hyphen? And you want to know why you get an index out of bounds exception? — Dawood ibn Kareem, Aug 06 '17 at 12:22
I'm still a student starting in Java. Pardon me for making seemingly idiotic mistakes. — Jason Hew, Aug 07 '17 at 04:50

score 0 · Answer 1 · answered Aug 06 '17 at 10:51

0

move the contact.length<11 validation on the left-side of the or (talking about the while statement).

Otherwise you are entering into the phNumValidation even with less than 11chars contacts. And that method is not prepared for that.

answered Aug 06 '17 at 10:51

albert_nil

1,648
7
9

Rajeev Ranjan · Answer 2 · 2017-08-06T11:13:16.650

You get the exception because you tend to pass contact of length <=4 to phNumValidation function and do a substring without checking the length first. Below code will not throw any exception as length would be checked first. While loop would also need not call the function again.

  boolean valid = false;
  do{
        System.out.print("Contact Number (01X-XXXXXXX) :");
        contact = scan.next();
        if(!phNumValidation(contact)){
            System.out.println("Invalid Phone Number. Please try again.");
            System.out.println("");
        }else{
            valid = true;
        }


    }while(!valid);


public static boolean phNumValidation(String contact){
    boolean valid = true;

    if(contact.length() == 11){
    String dash = contact.substring(3, 4);
    valid = true;
        valid = contact.startsWith("01");
        valid = dash.matches("-");
    }
    else{
        valid = false;
    }

    return valid;
}

score 0 · Answer 3 · answered Aug 06 '17 at 11:03

It's time for you to use regular expressions, for example this is how my validation method would look like.

public static boolean phNumValidation(String contact){
    return contact.matches("01\\d-\\d{7}");
}

This method validates length, format all at once.

Keep on having StringIndexOutOfBoundsException for this part

3 Answers3