How do I ensure that the user does not enter numbers in his / her name?

Question

I am asking the user to enter his/her name. What can I do so that numbers won't be excepted?

String name = " ";
System.out.println("Enter Name");
name = Keyboard.readString();

can you tell me what is regex? I am new to programing – Kurt Camilleri Oct 20 '13 at 15:34 — Kurt Camilleri, Oct 20 '13 at 15:34

score 4 · Accepted Answer · answered Oct 20 '13 at 15:45

4

Use regex to check the input and a loop to get a good answer:

String name = "";
while (true) {
    System.out.println("Enter Name");
    name = Keyboard.readString();
    if (name.matches("[a-zA-Z]+"))
        break;
    System.out.println("Invalid input. Enter letters only");
}

answered Oct 20 '13 at 15:45

Bohemian

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Does `matches` require the whole string to match? If not you'll need to anchor it (`^` and `$`) – Kevin Oct 20 '13 at 15:47
@Kevin yes. ^ and $ are implied with java's matches(), unlike JavaScript, perl, ruby etc – Bohemian Oct 20 '13 at 15:49
What poor design. Though not the first for Java. – Kevin Oct 20 '13 at 15:58
@kevin I agree :( if there's a defacto standard, unless you've got a good reason not to, just use it. See [this answer](http://stackoverflow.com/questions/7281469/why-is-java-util-observable-not-an-abstract-class/7284322#7284322) for a few more design errors in java – Bohemian Oct 20 '13 at 21:04

codingenious · Answer 2 · 2013-10-20T15:42:54.200

0

boolean numberOrNot = name.matches(".*\\d.*");

numberOrNot will be true if it name has any number, else it will be false.

regex means, Regular Expressions. -?\\d+ is a regex.

-?: negative sign, could have none or one
\\d+: one or more digits

But this is validation, I don't think you can put limitation on console.

edited Oct 20 '13 at 15:42

answered Oct 20 '13 at 15:37

codingenious

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how do you think I should do it then @Pshemo – Kurt Camilleri Oct 20 '13 at 15:43
thanks a lot .. but since I am a beginner I prefer to use the answer by Bohemian, which is easier to understand.. but thanks a lot for your help just the same :) – Kurt Camilleri Oct 20 '13 at 15:54

Pshemo · Answer 3 · 2013-10-21T02:11:51.553

You cant make user put only characters in console and nothing else while typing, but you can validate his input and check if it contains only alphabetic characters after he put it and in case of invalid one ask user to type his data again.

To check if String contains only alphabetic characters you can iterate over all its characters and use Character.isAlphabetic(character) on them or just use matches with regex like this one userData.matches("\\p{IsAlphabetic}+");

Character.isAlphabetic and \\p{IsAlphabetic} has advantage over checking a-zA-Z range because it will also accept non English characters like ą, ę.

since I am a beginner it is good for me to use a-z range.. but thanks a lot for your help — Kurt Camilleri, Oct 20 '13 at 15:55

How do I ensure that the user does not enter numbers in his / her name?

3 Answers3