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Java Java Data Structures - Retired Efficiency! Call Center Queue

Posted by Matthew Earlywine
Matthew Earlywine
2,560 Points

What am I missing here with my do while loop?

This is a Call Center application. There is a group of Customer Support Representatives that assist Customers. When representatives become available they enter the queue. The acceptCustomer method gets called when new customer phones in. I’ve left 3 things for you todo in the comments below. All other code is only for your reference, no need to change it.

CallCenter.java 
import java.util.ArrayDeque;
import java.util.Queue;

public class CallCenter {
  Queue<CustomerSupportRep> mSupportReps;

  public CallCenter(Queue<CustomerSupportRep> queue) {
    mSupportReps = queue;
  }

  public void acceptCustomer(Customer customer) {
    CustomerSupportRep csr;
    /********************************************
     * TODO (1) 
     * Wait until there is an available rep in the queue.
     * While there is not one available, playHoldMusic
     * HINT: That while assignmentcheck loop syntax we used to 
      *      read files seems pretty similar
     ********************************************
     */
    do {
      playHoldMusic();
    } while (mSupportReps.peek() == null);

    /********************************************
     * TODO (2) 
     * After we have assigned the rep, call the 
     * assist method and pass in the customer
     ********************************************
     */
     csr = mSupportReps.poll();
     csr.assist(customer);

    /********************************************
     * TODO (3) 
     * Since the customer support rep is done with
     * assisting, put them back into the queue.
     ********************************************
     */
   mSupportReps.add(csr);

  }

  public void playHoldMusic() {
    System.out.println("Smooooooth Operator.....");
  }

}
CustomerSupportRep.java 
import java.util.List;
import java.util.ArrayList;

public class CustomerSupportRep {
  private String mName;
  private List<Customer> mAssistedCustomers;

  public CustomerSupportRep(String name) {
    mName = name;
    mAssistedCustomers = new ArrayList<Customer>();
  }

  public void assist(Customer customer) {
    System.out.printf("Hello %s, my name is %s, how can I assist you.%n",
                      customer.getName(),
                      mName);
    System.out.println("...");
    System.out.println("Is there anything else I can help you with?");
    mAssistedCustomers.add(customer);
  }

  public List<Customer> getAssistedCustomers() {
    return mAssistedCustomers;
  }

}
Customer.java 
public class Customer {
  private String mName;

  public Customer(String name) {
    mName = name;
  }

  public String getName() {
    return mName;
  }

}

1 Answer

jcorum
jcorum
71,830 Points

This works:

    while (mSupportReps.peek() == null) {
      playHoldMusic();  
    }
    csr = mSupportReps.poll();

    /********************************************
     * TODO (2) 
     * After we have assigned the rep, call the 
     * assist method and pass in the customer
     ********************************************
     */
    csr.assist(customer);
    /********************************************
     * TODO (3) 
     * Since the customer support rep is done with
     * assisting, put them back into the queue.
     ********************************************
     */
    mSupportReps.add(css);

It matches your code except that I replaced your do...while loop with a while loop.

I think the reason the editor doesn't like the do loop is that you will play music even if a rep is free.