Email Validation Errors

Question

I'm trying to make code that detects whether or not an email address is valid based on given conditions. My code seems to work for all the conditions except for when the email does not have an '@'. When it doesn't have an '@' I get a string out of bounds error. Any suggestions?

import java.util.Scanner;

public class email { public static void main (String[] args) {

//Create Scanner Object

Scanner stdin = new Scanner(System.in);

//prompt user for email address

System.out.print("Enter your email address: ");
String email = stdin.next();
email.length();

//shows location of @ and . characters

int atIndex = email.indexOf('@');
int finalperiodIndex = email.indexOf('.');
int periodIndex = email.indexOf('.');

//shows if email is valid or not

String invalid = "email is not valid";
String valid = "email is valid";
String location = email.substring(atIndex+1, email.length());
String userName = email.substring(0, atIndex);

//if the email does not have an '@' or '.' it is not valid

if((atIndex == -1) ||(periodIndex == -1)) {
    System.out.println(invalid);


//if the first character is a '@' it is not valid

}
else if (atIndex == 0) {
    System.out.println(invalid);

// if the last character is a '.' the email is invalid  

}
else if(periodIndex == email.length()-1) {
    System.out.println(invalid);
}
//if the final '.' is before the '@' the email is invalid

else if(finalperiodIndex < atIndex) {
    System.out.println(invalid);
}
//if there is a '.' before the '@' it's invalid

else if (email.indexOf('.') < email.indexOf('.')) {
    System.out.println(invalid);
}

//if there is no space between the '@' and '.' its invalid

else if (location.length()== -1) {
    System.out.println(invalid);
}
else {
    //end if 

    // print "valid" as well as domain and username

    System.out.println(valid);
    System.out.println("Username is: " + userName);
    System.out.println("Domain is: " + location);

This sort of question has been asked [many times on this site](https://www.google.com/search?q=java+email+address+validation+site:stackoverflow.com) and on others. — Hovercraft Full Of Eels, Sep 26 '18 at 01:37
To be fair they aren't asking _how_ to validate an email, but rather asking about a specific error in their implementation. — Daedalus, Sep 26 '18 at 01:42
@ScaryWombat I have no doubt this error has been asked about, but the question you linked isn't the about the same exception as OP's. — Daedalus, Sep 26 '18 at 01:57
@Daedalus: I agree which is why I did not dupe-hammer the question, but rather pseudo-dup'd it — Hovercraft Full Of Eels, Sep 26 '18 at 02:11
Thanks, I will check that place out, sorry for asking a repeated question. — Sam Schmitt, Sep 26 '18 at 02:16

score 0 · Answer 1 · answered Sep 26 '18 at 01:36

0

Move the if((atIndex == -1) ||(periodIndex == -1)) check higher up in your implementation, before your substring attempts. Also, make sure you stop the validation logic if this condition is true (not sure where this is implemented, but if it was a method then make sure to return false, or throw an exception, or whatever).

answered Sep 26 '18 at 01:36

Daedalus

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10
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Sorry this might be a dumb question but I am really new to java. How would I stop the validation logic if the condition is true? I also added the rest of the code if that helps. – Sam Schmitt Sep 26 '18 at 01:45
Since you are just putting this inside of a main method (ie: `public static void main(String [] args) { ... }`) then you can just use `return;` after printing out your `System.out.println(invalid);` statement. – Daedalus Sep 26 '18 at 01:48
I just tried adding the return; to it and I am still getting the same error. – Sam Schmitt Sep 26 '18 at 01:54
Might be easier to get "help me figure out Java"-style help like this on a different forum, like https://www.reddit.com/r/javahelp/ . – Daedalus Sep 26 '18 at 02:10

Email Validation Errors

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