fix the deleting method

sk1418 · sk1418 · commit 678d42ba977c · 2021-02-28T11:53:48.000+01:00
diff --git a/data-structures/src/main/java/com/baeldung/circularlinkedlist/CircularLinkedList.java b/data-structures/src/main/java/com/baeldung/circularlinkedlist/CircularLinkedList.java
@@ -5,7 +5,7 @@
 
 public class CircularLinkedList {
 
-    final Logger LOGGER = LoggerFactory.getLogger(CircularLinkedList.class);
+    final Logger logger = LoggerFactory.getLogger(CircularLinkedList.class);
 
     private Node head = null;
     private Node tail = null;
@@ -42,24 +42,29 @@ public boolean containsNode(int searchValue) {
     }
 
     public void deleteNode(int valueToDelete) {
-
         Node currentNode = head;
-
-        if (head != null) {
-            if (currentNode.value == valueToDelete) {
-                head = head.nextNode;
-                tail.nextNode = head;
-            } else {
-                do {
-                    Node nextNode = currentNode.nextNode;
-                    if (nextNode.value == valueToDelete) {
-                        currentNode.nextNode = nextNode.nextNode;
-                        break;
+        if (head == null) {
+            return;
+        }
+        do {
+            Node nextNode = currentNode.nextNode;
+            if (nextNode.value == valueToDelete) {
+                if (tail == head) {
+                    head = null;
+                    tail = null;
+                } else {
+                    currentNode.nextNode = nextNode.nextNode;
+                    if (head == nextNode) {
+                        head = head.nextNode;
+                    }
+                    if (tail == nextNode) {
+                        tail = currentNode;
                     }
-                    currentNode = currentNode.nextNode;
-                } while (currentNode != head);
+                }
+                break;
             }
-        }
+            currentNode = nextNode;
+        } while (currentNode != head);
     }
 
     public void traverseList() {
@@ -68,7 +73,7 @@ public void traverseList() {
 
         if (head != null) {
             do {
-                LOGGER.info(currentNode.value + " ");
+                logger.info(currentNode.value + " ");
                 currentNode = currentNode.nextNode;
             } while (currentNode != head);
         }
diff --git a/data-structures/src/test/java/com/baeldung/circularlinkedlist/CircularLinkedListUnitTest.java b/data-structures/src/test/java/com/baeldung/circularlinkedlist/CircularLinkedListUnitTest.java
@@ -1,10 +1,10 @@
 package com.baeldung.circularlinkedlist;
 
+import org.junit.Test;
+
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-import org.junit.Test;
-
 public class CircularLinkedListUnitTest {
 
     @Test
@@ -23,7 +23,7 @@ public void givenACircularLinkedList_WhenLookingForNonExistingElement_ThenReturn
     }
 
     @Test
-    public void givenACircularLinkedList_WhenDeletingElements_ThenListDoesNotContainThoseElements() {
+    public void givenACircularLinkedList_WhenDeletingInOrderHeadMiddleTail_ThenListDoesNotContainThoseElements() {
         CircularLinkedList cll = createCircularLinkedList();
 
         assertTrue(cll.containsNode(13));
@@ -39,6 +39,32 @@ public void givenACircularLinkedList_WhenDeletingElements_ThenListDoesNotContain
         assertFalse(cll.containsNode(46));
     }
 
+    @Test
+    public void givenACircularLinkedList_WhenDeletingInOrderTailMiddleHead_ThenListDoesNotContainThoseElements() {
+        CircularLinkedList cll = createCircularLinkedList();
+
+        assertTrue(cll.containsNode(46));
+        cll.deleteNode(46);
+        assertFalse(cll.containsNode(46));
+
+        assertTrue(cll.containsNode(1));
+        cll.deleteNode(1);
+        assertFalse(cll.containsNode(1));
+
+        assertTrue(cll.containsNode(13));
+        cll.deleteNode(13);
+        assertFalse(cll.containsNode(13));
+    }
+
+    @Test
+    public void givenACircularLinkedListWithOneNode_WhenDeletingElement_ThenListDoesNotContainTheElement() {
+        CircularLinkedList cll = new CircularLinkedList();
+        cll.addNode(1);
+        cll.deleteNode(1);
+        assertFalse(cll.containsNode(1));
+    }
+
+
     private CircularLinkedList createCircularLinkedList() {
         CircularLinkedList cll = new CircularLinkedList();
 
