diff --git a/data_structures/CircleLinkedList.java b/data_structures/CircleLinkedList.java new file mode 100644 index 000000000..cf03cd7cd --- /dev/null +++ b/data_structures/CircleLinkedList.java @@ -0,0 +1,42 @@ +public class CircleLinkedList{ + private static class Node{ + Node next; + E value; + private Node(E value, Node 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 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(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(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 iterator = head.next; + Node 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; + + } + + } +