Created and tested the queue data structure

src/main/java/net/jrtechs/www/DataStructures/Lists/Queue/IQueue.java

@@ -0,0 +1,22 @@
+package net.jrtechs.www.DataStructures.Lists.Queue;
+
+/**
+ * @author Jeffery Russell 8-26-18
+ */
+public interface IQueue<E>
+{
+    /**
+     * Adds a new element to the end of the queue
+     *
+     * @param element object to add
+     */
+    public void enqueue(E element);
+
+
+    /**
+     * Removes an object from the queue.
+     *
+     * @return the object removed
+     */
+    public E dequeue();
+}

src/main/java/net/jrtechs/www/DataStructures/Lists/Queue/Queue.java

@@ -0,0 +1,84 @@
+package net.jrtechs.www.DataStructures.Lists.Queue;
+
+
+import net.jrtechs.www.DataStructures.Node;
+
+
+/**
+ * Data structure which stores objects in a linked
+ * list where objects inserted first are removed first,
+ * and where objects inserted last are removed last.
+ *
+ * @author Jeffery Russell 8-26-18
+ * @param <E> generic data type
+ */
+public class Queue<E> implements IQueue<E>
+{
+    /** Head node */
+    private Node<E> head;
+
+    /**Stored tail to make insertions o(1) */
+    private Node<E> tail;
+
+
+    /**
+     * Creates an empty queue
+     */
+    public Queue()
+    {
+        this.head = null;
+        this.tail = null;
+    }
+
+
+    /**
+     * Creates a queue with a single element in it
+     *
+     * @param element object to add to queue
+     */
+    public Queue(E element)
+    {
+        this.head = new Node<>(element);
+        this.tail = head;
+    }
+
+
+    /**
+     * Adds a single element to the queue
+     *
+     * @param element object to add
+     */
+    @Override
+    public void enqueue(E element)
+    {
+        Node<E> newElement = new Node<>(element);
+        if(this.tail == null)
+        {
+            this.head = newElement;
+            this.tail = newElement;
+        }
+        else
+        {
+            this.tail.setNext(newElement);
+            this.tail = newElement;
+        }
+    }
+
+
+    /**
+     * Removes the element from the front of the queue
+     *
+     * @return element removed
+     */
+    @Override
+    public E dequeue()
+    {
+        if(this.head != null)
+        {
+            E temp = this.head.getData();
+            this.head = this.head.getNext();
+            return temp;
+        }
+        return null;
+    }
+}

src/test/java/net/jrtechs/www/DataStructures/Lists/QueueTest.java

@@ -0,0 +1,56 @@
+package net.jrtechs.www.DataStructures.Lists;
+
+import net.jrtechs.www.DataStructures.Lists.Queue.Queue;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertNotNull;
+import static junit.framework.TestCase.assertNull;
+import static junit.framework.TestCase.assertTrue;
+
+/**
+ * JUnit tests for
+ * {@link net.jrtechs.www.DataStructures.Lists.Queue.Queue}
+ *
+ * @author Jeffery Russell 8-26-18
+ */
+public class QueueTest
+{
+    @Test
+    public void testCreation()
+    {
+        assertNotNull(new Queue<>());
+
+        assertNotNull(new Queue<>(12.0));
+    }
+
+
+    @Test
+    public void testInsertion()
+    {
+        Queue<String> words = new Queue<>();
+
+        words.enqueue("One");
+
+        words.enqueue("Two");
+
+        words.enqueue("Three");
+
+        assertNotNull(words.dequeue());
+    }
+
+    @Test
+    public void testDequeue()
+    {
+        Queue<String> words = new Queue<>();
+
+        words.enqueue("One");
+        words.enqueue("Two");
+        words.enqueue("Three");
+
+        assertTrue(words.dequeue().equals("One"));
+        assertTrue(words.dequeue().equals("Two"));
+        assertTrue(words.dequeue().equals("Three"));
+
+        assertNull(words.dequeue());
+    }
+}

src/test/java/net/jrtechs/www/DataStructures/Lists/StackTest.java

@@ -7,6 +7,11 @@ import static junit.framework.TestCase.assertFalse;
 import static junit.framework.TestCase.assertNotNull;
 import static junit.framework.TestCase.assertTrue;
 
+/**
+ * JUnit tests for {@link Stack}
+ *
+ * @author Jeffery Russell 8-25-18
+ */
 public class StackTest
 {