64 lines
2.1 KiB
Java
64 lines
2.1 KiB
Java
package DataStructures.Lists;
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public class CircleLinkedList<E> {
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private static class Node<E> {
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Node<E> next;
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E value;
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private Node(E value, Node<E> next) {
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this.value = value;
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this.next = next;
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}
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}
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//For better O.O design this should be private allows for better black box design
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private int size;
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//this will point to dummy node;
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private Node<E> head;
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//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;
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public CircleLinkedList() {
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//creation of the dummy node
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head = new Node<E>(null, head);
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size = 0;
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}
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// getter for the size... needed because size is private.
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public int getSize() {
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return size;
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}
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// 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.
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public void append(E value) {
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if (value == null) {
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// we do not want to add null elements to the list.
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throw new NullPointerException("Cannot add null element to the list");
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}
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//head.next points to the last element;
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head.next = new Node<E>(value, head);
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size++;
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}
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public E remove(int pos) {
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if (pos > size || pos < 0) {
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//catching errors
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throw new IndexOutOfBoundsException("position cannot be greater than size or negative");
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}
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//we need to keep track of the element before the element we want to remove we can see why bellow.
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Node<E> before = head;
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for (int i = 1; i <= pos; i++) {
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before = before.next;
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}
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Node<E> destroy = before.next;
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E saved = destroy.value;
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// assigning the next reference to the the element following the element we want to remove... the last element will be assigned to the head.
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before.next = before.next.next;
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// scrubbing
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destroy = null;
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size--;
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return saved;
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}
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}
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