55 lines
2.1 KiB
Java
55 lines
2.1 KiB
Java
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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(){ return size;}
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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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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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Node<E> iterator = head.next;
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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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iterator = iterator.next;
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before = before.next;
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}
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E saved = iterator.value;
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// assigning the next referance 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 = iterator.next;
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// scrubbing
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iterator.next = null;
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iterator.value = null;
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return saved;
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}
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}
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