初学者正则表达式Java

Question

I'm wanting to write a Regular Expression that will match to one of several variations / common uses of a name.

I need to accept a user input, & then validate that the input matches one of the listed variations. If there is a match, I need to output that there was match, if not I should output that the input wasn't a match.

This is what I have so far:

import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class RegExMyName {

    public static void main(String[] args) {

        Scanner scan = new Scanner(System.in);

        System.out.println("Name: Daimon");
        System.out.println("Common Usages: Daimon, Daimo, Dai, daimon, daimo, DAIMON");
        System.out.println("Enter any of the variations listed only: ");

        //*** HELP REQUIRED WITH PATTERN BELOW - pat
        Pattern pat = Pattern.compile();
        Matcher match = pat.matcher(scan.nextLine());


        //***HELP REQUIRED WITH FIND BELOW
        if (match.find()){
            System.out.println("*** You entered a valid name ***");
        }else{
            System.out.println("*** You entered an invalid name ***");
        }




    }
}

I would like some help constructing the pattern or receiving suggestions for alternative methods that would accomplish the same thing.

Thanks.

Answer 1

This pattern will match any of the strings Daimon , Daimo , Dai , daimon , daimo , DAIMON :

Pattern pattern = Pattern.compile("^([dD]aimon?|DAIMON|Dai)$");

Or a slightly more generous pattern would look something like this

Pattern pattern = Pattern.compile("^dai(mon?)?$",Pattern.CASE_INSENSITIVE);

Answer 2

I would not use regular expression for the case you described i would rather store the possible variations of the name eg in a List would validate the input just with a simple contains.

List<String> daimons = Arrays.asList("Daimon", "Daimo", "Dai", "daimon", "daimo", "DAIMON");

I don't see really the power of the regex for your example. If i would not see your solution probably my would be something similar:

public class RegExMyName {

public static void main(String[] args) {

    Scanner scan = new Scanner(System.in);

    List<String> daimons = Arrays.asList("Daimon", "Daimo", "Dai", "daimon", "daimo", "DAIMON");
    StringBuilder diamonCommonUsage = new StringBuilder();
    for(String daimonVariations : daimons) {
      diamonCommonUsage.append(daimonVariations);
      diamonCommonUsage.append(", "); //+ remove the last ","
    }        

    System.out.println("Name: Daimon");
    System.out.println("Common Usages: " + diamonCommonUsage.toString());
    System.out.println("Enter any of the variations listed only: ");

    if (match.find(daimons.contains(scan.nextLine()))){
        System.out.println("*** You entered a valid name ***");
    }else{
        System.out.println("*** You entered an invalid name ***");
    }
}

}