Question

((Java)) Ask the user for some letters. Display, in alphabetical order, a list of email address domains from users that have a first name that begins with the inputted letters.

A domain is the characters after the @ symbol.

[email protected]

Standard Input	Files in the same directory
Hea	mock-data.csv

Output
== Domain Lookup ==\n
Enter some letters\n
Here are the domains of the users that begin with Hea\n
free.fr\n
Found 1 domain(s)\n

Standard Input	Files in the same directory
He	mock-data.csv

Output
== Domain Lookup ==\n
Enter some letters\n
Here are the domains of the users that begin with He\n
apple.com\n
artisteer.com\n
cnbc.com\n
free.fr\n
google.it\n
ihg.com\n
indiatimes.com\n
mtv.com\n
myspace.com\n
pbs.org\n
printfriendly.com\n
spiegel.de\n
surveymonkey.com\n
wufoo.com\n
Found 14 domain(s)\n

Standard Input	Files in the same directory
X	mock-data.csv

Output
== Domain Lookup ==\n
Enter some letters\n
Here are the domains of the users that begin with X\n
tumblr.com\n
Found 1 domain(s)\n

Standard Input	Files in the same directory
Fer	mock-data.csv

Output
== Domain Lookup ==\n
Enter some letters\n
Here are the domains of the users that begin with Fer\n
dailymail.co.uk\n
ebay.co.uk\n
indiegogo.com\n
rediff.com\n
unblog.fr\n
Found 5 domain(s)\n

mock-data.csv

Sheilds,Nisse,[email protected],New York
Lamblin,Codie,[email protected],New Jersey
Bagenal,Emlynne,[email protected],Texas
Krier,Sacha,[email protected],South Carolina
Sammonds,Diana,[email protected],Virginia
Franceschielli,Amara,[email protected],Texas
Coulston,Nicholas,[email protected],Texas
Cadigan,Sampson,[email protected],Georgia
Simanenko,Eleanore,[email protected],North Carolina
Jayes,Brooke,[email protected],California
Beardsdale,Ferdinanda,[email protected],California
Pandie,Melamie,[email protected],Maryland
Dandie,Clement,[email protected],South Carolina
Keenor,Mitchael,[email protected],Oklahoma
Joinsey,Cole,[email protected],Texas
Hanington,Warren,[email protected],Ohio
Bunny,Mose,[email protected],Georgia
Streader,Trumann,[email protected],California
Stenning,Hailee,[email protected],Louisiana
Lillywhite,Case,[email protected],California
Derisley,Ethelind,[email protected],Colorado
Carmichael,Raphaela,[email protected],Kansas
Shurey,Georgie,[email protected],North Carolina
Turpin,Laraine,[email protected],Michigan
Paulus,Tressa,[email protected],New York
Gon,Heidi,[email protected],Connecticut
Lindroos,Melisse,[email protected],Louisiana
Mathy,Glennis,[email protected],Ohio
Doul,Joellyn,[email protected],Texas
Skellern,Hersch,[email protected],New York
Brindley,Griz,[email protected],Virginia
Ghidoli,Georgena,[email protected],North Dakota
Lyddy,Knox,[email protected],New Jersey
Osborne,Fidole,[email protected],Minnesota
Chapelhow,Mick,[email protected],District of Columbia
Pennini,Filip,[email protected],Texas
Lindsey,Abagael,[email protected],Florida
Birrane,Kaye,[email protected],California
Simmens,Anthia,[email protected],Delaware

Answer 1

Please let me know if you have any doubts or you want me to modify the answer. And if you find this answer useful then don't forget to rate my answer as thumps up. Thank you! :)

import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;

public class Driver implements Comparable<PeopleData> {
    private static String first;
    private static String last;
    private static String email;
    private static String state;

    public static ArrayList<String> loadDatabase() {
        File f = new File("/Users/swapnil/IdeaProjects/DisplayNAme/src/mockdata.txt");
        ArrayList<String> result = new ArrayList<>();
        try {
            Scanner inputFile = new Scanner(f);

            while (inputFile.hasNextLine()) {

                String[] temp = inputFile.nextLine().split(",");
                first = temp[0];
                last = temp[1];
                email = temp[2];
                state = temp[3];

                result.add(String.valueOf(new PeopleData(first, last, email, state)));

            }

        } catch (FileNotFoundException e) {
            System.out.println("File is not found!");
        }
        return result;
    }

    public static String searchLetter(String search){
        if (getFirst().contains(search)){

        }
        return email;
    }
    public static String getFirst(){
        return first;
    }

    public static void main(String[] args){
        ArrayList<String> data = new ArrayList<>();
        loadDatabase();
        Scanner keyboard = new Scanner(System.in);

        System.out.println("== Domain Lookup ==");
        System.out.println("Enter some letters");

        System.out.println(data.size());
        System.out.println(data);
        String search = keyboard.nextLine();

        System.out.println(searchLetter(search));

    }

    @Override
    public int compareTo(PeopleData o) {
        return 0;
    }
}

----------------------------------------------------------------------------------------------------------------------------------
public class PeopleData {

    private String first;
    private String last;
    private String email;
    private String state;

    public PeopleData(String first, String last, String email, String state) {
        this.first = first;
        this.last = last;
        this.email = email;
        this.state = state;
    }
}

DisplayNAme /ldeaProjects/DisplayNAme] - .../src/Driver.java [DisplayNAme] ,DisplayNAme-src ƠDriver G Driverjava 렙 mockdata.txt . @ PeopleData.java Project * ÷ '嶚. I← import java.io.File import java.io.FiLeNotFoundException import java.util.ArrayList; import java.utit.scanner; DisplayNAme IdeaProjects/DisplayNAme idea out | public class Driver implements Comparable-PeopleData» { 6 Driver private static String first private static String last private static String email: private static String state mockdata.txt DisplayNAme.iml ▶ llll External Libraries 12 Scratches and Consoles public static ArrayList <String loadDatabase() File f = new Filel pathname. "/Users/swapnal/IdeaProjects/DisplayNAme/src/mackdata. txt"); ArrayList<Stringo result new ArrayListo); try t 15 16 Scanner inputFile = new Scanner(f); 18 while (inputFile.haslextLine)) 20 21 23 25 Stringl1 temp inputFile.nextLine().split( regex first temp [e]: last temp[1] email = temp [2]; state temp [3] 26 result.add(String.valueof(new PeopleData(first, last, email, state))) 30 /Library/Java/JavaVirtuaMachines/jdk-9.0.4.jdk/Contents/Home/bin/java "-javaagent:/Applications/IntelliJ IDEA CE.app/Contents/Lib/idea_rt.jar-51386:/Applications/IntelliJ IDEA CE.app/Contents/bi == Domain Lookup = Enter some letters Il Eb Meriel's [email protected] enail is Process finished with exit code 0 H Loaded classes are up to date. Nothing to reload. (moments ago