The Generic Queue Class : Queue « Collections Data Structure « Java

The Generic Queue Class


import java.util.LinkedList;

class GenQueue<E> {
  private LinkedList<E> list = new LinkedList<E>();

  public void enqueue(E item) {

  public E dequeue() {
    return list.poll();

  public boolean hasItems() {
    return !list.isEmpty();

  public int size() {
    return list.size();

  public void addItems(GenQueue<? extends E> q) {
    while (q.hasItems())

public class GenQueueTest {
  public static void main(String[] args) {
    GenQueue<Employee> empList;
    empList = new GenQueue<Employee>();

    GenQueue<HourlyEmployee> hList;
    hList = new GenQueue<HourlyEmployee>();
    hList.enqueue(new HourlyEmployee("T", "D"));
    hList.enqueue(new HourlyEmployee("G", "B"));
    hList.enqueue(new HourlyEmployee("F", "S"));


    while (empList.hasItems()) {
      Employee emp = empList.dequeue();
      System.out.println(emp.firstName + " " + emp.lastName);

class Employee {
  public String lastName;

  public String firstName;

  public Employee() {

  public Employee(String last, String first) {
    this.lastName = last;

    this.firstName = first;

  public String toString() {
    return firstName + " " + lastName;

class HourlyEmployee extends Employee {
  public double hourlyRate;

  public HourlyEmployee(String last, String first) {
    super(last, first);


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