QueueList

import java.util.LinkedList;
import java.util.Queue;

public class QueueSystem {

    private Queue<String> queue;
    private boolean isSupervisorOnline;
    private String supervisorUsername;

    public QueueSystem() {
        this.queue = new LinkedList<>();
        this.isSupervisorOnline = false;
        this.supervisorUsername = "";
    }

    public void joinQueue(String userName) {
        queue.add(userName);
        System.out.println(userName + " joined the queue.");
    }

    public int getPosition(String userName) {
        int position = 0;
        for (String user : queue) {
            if (user.equals(userName)) {
                return position;
            }
            position++;
        }
        return -1;
    }

    public void setSupervisorStatus(boolean online, String username) {
        isSupervisorOnline = online;
        supervisorUsername = online ? username : "";
        System.out.println("Supervisor " + (online ? username + " is now online" : "is now offline"));
    }

    public boolean isSupervisorOnline() {
        return isSupervisorOnline;
    }

    public String getSupervisorUsername() {
        return supervisorUsername;
    }

    public static void main(String[] args) {
        QueueSystem queueSystem = new QueueSystem();

    
        queueSystem.setSupervisorStatus(true, "Supervisor1");
        queueSystem.joinQueue("User1");
        queueSystem.joinQueue("User2");
        queueSystem.joinQueue("User3");

        System.out.println("User2 is at position: " + queueSystem.getPosition("User2"));
        System.out.println("Is Supervisor online? " + queueSystem.isSupervisorOnline());
        System.out.println("Supervisor username: " + queueSystem.getSupervisorUsername());
    }
}