CSVWriter.java

import java.io.FileWriter;
import java.util.*;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.TimeUnit;
import java.util.stream.Stream;

class CSVWriter {
    public static void main(String[] args) throws Exception {
        String[] names = {"beam", "maa", "saket", "alli", "jakid"}; 

        FileWriter csvWriter = new FileWriter("in.csv");
        csvWriter.append("firstName," + "age," + "email");
        csvWriter.append("\n");

        for (int i = 0; i < 10000; i++) {
            int age = new Random().nextInt(100);
            String name = names[new Random().nextInt(names.length)];
            String email = name + "@testemail.com";

            csvWriter.append(name + "," + age + "," + email);
            csvWriter.append("\n");
        }
        System.out.println("CSV File is written!");
        csvWriter.close();
    }
}