Thread: Priority Queue help

So I have to implement a checkout line using a priority queue. I'm really stuck. I have 3 classes, a Register class, Store class, and customer class.

Each customer has a service time which is the time it takes to check out.
There are ten registers.
Reach register has a line.
I have to add a customer based on which line has the lowest total service time.

I need help on how to get the total service time for a line of a register.

Here are my three classes so far:

Store:

import java.util.LinkedList;
import java.util.PriorityQueue;
 
 
public class Store {
 
	private PriorityQueue<Register> regs;
 
	public Store(){
		this.regs = new PriorityQueue<Register>();
 
		for(int i = 0;i<=10; i++){
			regs.add(new Register());
		}
	}
 
	private Register leastFullRegister() {
		double minWaitTime = Double.MAX_VALUE;
		Register leastFullRegister = null;
		for ( Register r : regs ) {
			if ( r.getTotalEnqueue() < minWaitTime ) {
				minWaitTime = r.getTotalEnqueue();
				leastFullRegister = r;
			}
		}
		return leastFullRegister;
	}
 
 
 
}

Register:

import java.util.PriorityQueue;
 
public class Register implements Comparable<Register> {
 
	private boolean open; // line open or not?
	private PriorityQueue<Customer> line; //the line of customers
	private int waitTime;
 
	 Register(){
	 open = false;
	 waitTime = 0;
 
	 this.line = new PriorityQueue<Customer>();
	}
 
	public double getTotalEnqueue(){
		double totalTime = 0;
 
		//go through every customer and get the serviceTimes and add them up 
		//This is to see which line is shorter
 
		return totalTime;
	}
 
	public void addCustomer(Customer c){
		line.add(c);
	}
 
	public Customer pollCustomer(){
		return line.poll();
	}
 
	public boolean isOpen(){
		// some how open and close lines?
		return true;
	}
 
	@Override
	public int compareTo(Register reg) {
 
		return 0;
	}
}

Customer

 
public class Customer {
 
	private double serviceTime;
	private int count;
 
	Customer(){
		serviceTime = Math.random() + 2;
		count = 0;
	}
 
	public double getServiceTime(){
		serviceTime = Math.random() + 2;
		count++;
		return serviceTime;
 
	}
 
	public int getCount(){
		return count;
	}
}

For each Register, iterate over the Customers and sum the service times.

Did you try it?

I said you would have to do it for all Registers. Each time you calculate the time compare it to the previous total time. If it is less then this Register has the shortest time.

for each Register {
    calculate time
    if time is less than previous shortest time
        update shortest time
        update shortest Register
    }
}

shortest Register now holds the Register with the shortest time.