Add linkedlist example.

Author: Kay Hudson

src/main/java/com/galvanize/LinkedList.java

@@ -0,0 +1,70 @@
+package com.galvanize;
+
+public class LinkedList {
+    private Node head;
+    private int size;
+
+    public LinkedList() {
+        this.size = 0;
+    }
+
+    public boolean isEmpty() {
+        return head == null;
+    }
+    public int count() {
+        return this.size;
+    }
+
+    public void addNode(Node node) {
+        if (head == null) {
+            head = node;
+        } else {
+            Node current = head;
+            while (current.getNext() != null) {
+                current = current.getNext();
+            }
+            current.setNext(node);
+        }
+        this.size++;
+    }
+
+    public Node getHead() {
+        return head;
+    }
+
+    public void setHead(Node head) {
+        this.head = head;
+    }
+
+    public Node find(Node node) {
+        if (head == node) {
+            return head;
+        }
+        Node current = head.getNext();
+        while (current != null) {
+            if (current == node) return current;
+            current = current.getNext();
+        }
+        return null;
+    }
+
+    public void removeNode(Node node) {
+        if (head != null && head == node) {
+            head = node;
+            this.size--;
+        } else {
+            Node previous = head;
+            Node current = head.getNext();
+            while (current != null) {
+                if (current == node) {
+                    previous.setNext(current.getNext());
+                    this.size--;
+                    break;
+                } else {
+                    previous = current;
+                    current = current.getNext();
+                }
+            }
+        }
+    }
+}

src/test/java/LinkedListTestCase.java

@@ -0,0 +1,59 @@
+import com.galvanize.LinkedList;
+import com.galvanize.Node;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+public class LinkedListTestCase {
+    LinkedList linkedList;
+
+    @BeforeEach
+    void setUp() {
+        linkedList = new LinkedList();
+    }
+
+    @Test
+    void testListEmpty() {
+        assertTrue(linkedList.isEmpty());
+    }
+
+    @Test
+    void testAddNode() {
+        Node node = new Node("Sword");
+        linkedList.addNode(node);
+        assertEquals(node, linkedList.getHead());
+    }
+
+    @Test
+    void testAddManyNodesChangesSize() {
+        linkedList.addNode(new Node("A"));
+        linkedList.addNode(new Node("B"));
+        linkedList.addNode(new Node("C"));
+        assertEquals(3, linkedList.count());
+    }
+
+    @Test
+    void testFindNode() {
+        Node aNode = new Node("A");
+        Node bNode = new Node("B");
+        linkedList.addNode(aNode);
+        linkedList.addNode(bNode);
+        Node result = linkedList.find(aNode);
+        assertEquals(aNode, result);
+    }
+
+    @Test
+    void testRemoveNodeSuccess() {
+        Node aNode = new Node("A");
+        Node bNode = new Node("B");
+        Node cNode = new Node("C");
+        Node dNode = new Node("D");
+        linkedList.addNode(aNode);
+        linkedList.addNode(bNode);
+        linkedList.addNode(cNode);
+        linkedList.addNode(dNode);
+        linkedList.removeNode(cNode);
+        assertEquals(3, linkedList.count());
+        assertEquals(bNode.getNext(), dNode);
+    }
+}