Add singly linked list

MohamedBechir · MohamedBechir · commit f82bf1a14918 · 2020-04-28T01:39:18.000+01:00
diff --git a/src/main/java/com/dataStructures/SinglyLinkedList.java b/src/main/java/com/dataStructures/SinglyLinkedList.java
@@ -0,0 +1,102 @@
+package com.dataStructures;
+
+
+
+
+public class SinglyLinkedList<T> {
+	
+     /**
+     * Define a node in the singly linked list
+     */
+	private static class Node<T> {
+        T data;
+        Node<T> next;
+ 
+        Node(T data) {
+            this.data = data;
+        }
+    }
+
+	 /**
+     * Reference to the first node of the singly linked list
+     */	
+    private Node<T> head;    
+	
+	/**
+    * Method to return the size of the singly linked list
+    */	
+	public int size() {
+		int size = 0;
+	    Node<T> node = head;
+	    while (node != null) {
+	        ++size;
+	        node = node.next;
+	    }
+	    return size;
+	}
+		 
+	/**
+    * Method to add a node at the end of the singly linked list
+    */		 
+	 public void add(T data) {
+		Node<T> newNode = new Node<>(data);
+		    if (head == null) {
+		        head = newNode;
+		    } else {
+		        Node<T> last = head;
+		        while (last.next != null) {
+		            last = last.next;
+		        }
+		        last.next = newNode;
+		    }
+		}
+	 
+     /**
+      * Method to add a node at the beginning of the singly linked list
+      */
+     public void insertAtStart (T data) {
+    	 Node<T> node = new Node<>(data);
+		 node.data = data;
+		 node.next = null;
+		 node.next = head;
+		 head = node;
+    	 
+     }
+     
+     /**
+      * Method to remove a node at any position in the singly linked list
+      */
+    public void remove(int position) {
+        Node<T> prev = null, node = head;
+    	    while (position > 0 && node != null) {
+    	        --position;
+    	        prev = node;
+    	        node = node.next;
+    	    }
+    	    if (node != null) {
+    	        if (prev == null) {
+    	            head = node.next;
+    	        } else {
+    	            prev.next = node.next;
+    	        }
+    	    }
+    	}
+     
+     /**
+      * Method to print the content of the singly linked list for better
+      *  understanding
+      */
+    public void printContent() {
+ 	    StringBuilder sb = new StringBuilder();
+ 	    Node<T> node = head;
+ 	    while (node != null) {
+ 	        sb.append(node.data).append('-').append('>');
+ 	        node = node.next;
+ 	    }
+ 	    int lastComma = sb.lastIndexOf(",");
+ 	    if (lastComma != -1) {
+ 	        sb.deleteCharAt(lastComma);
+ 	    }
+ 	    System.out.println(sb);
+ 	}
+ 		 }
diff --git a/src/test/java/com/dataStructures/SinglyLinkedListTest.java b/src/test/java/com/dataStructures/SinglyLinkedListTest.java
@@ -0,0 +1,60 @@
+package com.dataStructures;
+
+import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+
+
+public class SinglyLinkedListTest {
+
+	 private SinglyLinkedList<Integer> MySinglyLinkedList = new SinglyLinkedList<>();
+	 
+	    @Test
+	    public void emptyTest() {
+	        Assertions.assertEquals(0, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	    }
+	 
+	    @Test
+	    public void addTest() {
+	        MySinglyLinkedList.add(1);
+	        Assertions.assertEquals(1, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.add(42);
+	        Assertions.assertEquals(2, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.add(2);
+	        MySinglyLinkedList.add(3);
+	        Assertions.assertEquals(4, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	    }
+	    
+	    @Test
+	    public void removeTest() {
+	        MySinglyLinkedList.add(1);
+	        MySinglyLinkedList.add(2);
+	        MySinglyLinkedList.add(3);
+	        MySinglyLinkedList.add(4);
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.remove(3);
+	        Assertions.assertEquals(3, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.remove(0);
+	        Assertions.assertEquals(2, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.remove(0);
+	        Assertions.assertEquals(1, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	 
+	        MySinglyLinkedList.remove(0);
+	        Assertions.assertEquals(0, MySinglyLinkedList.size());
+	        MySinglyLinkedList.printContent();
+	    }
+	 
+
+ 
+}
