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Java Java Data Structures - Retired Efficiency! Call Center Queue

Getting stuck on the Call Center quiz.

I am able to play the wait music fine with a do while loop. I seem to be calling assist because I'm seeing the messaging in the preview. When I try to add the csr back to the queue I always get an error asking if I called assist.

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.poll()) == null);

    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(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

Christopher Augg
Christopher Augg
21,223 Points

Hello Andrew,

When you use the poll method it removes the head item from the queue. Therefore, if you poll again and the item is no longer there, you cannot retrieve it. You should consider a different queue method. You can look at the following for a good reference:

http://docs.oracle.com/javase/7/docs/api/java/util/Queue.html

Regards,

Chris