Stuck on how to make string character input only

Question

for the last few hours i've been trying to get this code to only allow character input, as its for accepting names.. I have been following the same type of method i used to allow only integers, but with no luck. any advice would be great, Here is my code

            String name;
            System.out.println("Enter student's name: ");
            name = in.nextLine();
            while (!in.nextLine().matches("[a-zA-Z]"));
            {   
                System.out.println("Please enter a valid name!: ");
                in.next();
                }
            name = in.nextLine();

You might like checking [this question](http://stackoverflow.com/questions/5238491/check-if-string-contains-only-letters) — Joqus, Dec 04 '13 at 01:58
You consume your valid name in the checking process anyway... — Sinkingpoint, Dec 04 '13 at 02:08
Are you trying to get first name, mi, and last name, is that what the single char check is for? — Paul Samsotha, Dec 04 '13 at 02:08

score 2 · Accepted Answer · answered Dec 04 '13 at 02:01

2

Your regex checks if the line matches exactly one [a-zA-Z] character. You probably want to check at least one: [a-zA-Z]+

Bear in mind that the way you are checking, you won't get what you have checked in the variable name, as you are consuming it in your checking. Can I propose an alternative:

System.out.println("Enter student's name: ");
String name = in.nextLine();
while(!name.matches("[a-zA-Z]+")){
    System.out.println("Please enter a valid name!");
    name = in.nextLine();
}

answered Dec 04 '13 at 02:01

Sinkingpoint

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How could i get this to allow spaces? – user3050340 Dec 04 '13 at 02:16
1

@user3050340 Just add a space to the regex: `[a-zA-Z ]+` This essentially means any character between the brackets, at least once. – Sinkingpoint Dec 04 '13 at 02:17
Ah i see, i understand. Thanks for your help. My programme is up and running now :) – user3050340 Dec 04 '13 at 02:21

score 1 · Answer 2 · edited Dec 04 '13 at 02:21

1

I'm not too familiar with regex, personally, so I would just go with a method that takes a string and determines whether it is only comprised of the alphabets.

[EDIT] Shame on me, the method for testing if a character is a letter is static. Thanks to dansalmo for reminding me.

public static boolean isAlphabetic(String s) {
    for(int i = 0; i < s.length(); i++) {
        if (!Character.isLetter(s.charAt(i))) return false;
    }
    return true;
}

edited Dec 04 '13 at 02:21

dansalmo

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answered Dec 04 '13 at 02:01

Vineet Kosaraju

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Use `if (!Character.isLetter(s.charAt(i))) return false`. Otherwise Static Error: No method in Character with name 'isLetter' matches this invocation. – dansalmo Dec 04 '13 at 02:10

score 0 · Answer 3 · answered Dec 04 '13 at 02:02

0

Did you check the value of the variable name? While you assign the input to name , you seem to read the next line for regex check. Remove the in.next too and it should work fine

answered Dec 04 '13 at 02:02

Suresh C Nair

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score 0 · Answer 4 · answered Dec 04 '13 at 02:17

0

Similar to Bucco's solution but iterating over a char array:

public static boolean isAlphabetic(String s) {
    for(char c : s.toCharArray())
        if (!Character.isLetter(c)) return false;
    return true;
}

answered Dec 04 '13 at 02:17

dansalmo

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Stuck on how to make string character input only

4 Answers4