Merge pull request #26 from Moro-Code/master

CircleLinkedList

Author: dynamitechetan

data_structures/CircleLinkedList.java

@@ -0,0 +1,42 @@
+public class CircleLinkedList<E>{
+     private static class Node<E>{
+         Node<E> next;
+         E value;
+         private Node(E value, Node<E> next){
+              this.value = value;
+              this.next = next;
+         }
+     }
+     private int size; //For better O.O design this should be private allows for better black box design
+     private Node<E> head; //this will point to dummy node;
+     public CircleLinkedList(){ //constructer for class.. here we will make a dummy node for circly linked list implementation with reduced error catching as our list will never be empty;
+         head = new Node<E>(null,head); //creation of the dummy node
+         size = 0;
+     }
+     public int getSize(){ return size;} // getter for the size... needed because size is private.
+     public void append(E value){ // for the sake of simplistiy this class will only contain the append function or addLast other add functions can be implemented however this is the basses of them all really.
+         if(value == null){
+         	throw new NullPointerException("Cannot add null element to the list"); // we do not want to add null elements to the list.
+         }
+         head.next = new Node<E>(value,head); //head.next points to the last element;
+         size++;}
+     public E remove(int pos){
+     	if(pos>size || pos< 0){
+     		throw new IndexOutOfBoundsException("position cannot be greater than size or negative"); //catching errors
+     	}
+     	Node<E> iterator = head.next; 
+     	Node<E> before = head; //we need to keep track of the element before the element we want to remove we can see why bellow.
+     	for(int i = 1; i<=pos; i++){
+            iterator = iterator.next;
+            before = before.next;   
+     	}
+     	E saved = iterator.value;
+     	before.next = iterator.next; // assigning the next referance to the the element following the element we want to remove... the last element will be assigned to the head.
+     	iterator.next = null; // scrubbing 
+     	iterator.value = null; 
+     	return saved;
+
+     	}
+
+     }
+