How to only accept a String with certain characters in Java

Question

for (int i = 0; i < d.getFornavn().length(); i++) {
    char c = d.getFornavn().charAt(i);  
    if ((c > 'a' && c < 'z') || (c > 'A' && c < 'Z') || ( c == ' ' || c == '-')) {
        flag = true;
    }
}

Hi! I'm trying to make a function that checks a string if it only has certain characters (only az, AZ, the norwegian letters å,æ,ø,Å,Æ,Ø, whitespace and hyphen, but I'm having some trouble with that. I tried doing what you see here, but it's not working how I hoped it would (I didn't implement the norwegian letters yet, because I'm clueless on how to do that).

I'm starting to think there must be a simpler way to check for this, but I haven't heard about anything.

Any thoughts?

Answer 1

您可以使用正则表达式：

flag = d.getFornavn().matches("[a-zA-zåæøÅÆØ -]+");

Answer 2

The approach you are using will give result based on last character of your string or only one character . Since it is setting flag for each char. To reject all invalid strings you can simply

bool flag = true;
for (int i = 0; i < d.getFornavn().length(); i++) {
    char c = d.getFornavn().charAt(i);  
    if ((!c > 'a' && c < 'z') && !(c > 'A' && c < 'Z') && ( c != ' ' || c != '-')) {
       flag = false;
       break;
    }
}

Accept only those strings which flag true

Answer 3

You could search on a string

public static void main(String[] args) {
    String s = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ - åæøÅÆØ";
    String yourstr = "Ø123456";
    System.out.println(myfunc(s, yourstr));
}
private static boolean myfunc(String s, String yourstr) {
    for (int i = 0; i < yourstr.length(); i++) {
        char c = yourstr.charAt(i);  
        if (s.indexOf(c) > 0) {
            return true;
        }
    }
    return false;
}