class ListNode { public ListNode next; public Object data; public ListNode(Object data, ListNode next) { this.next = next; this.data = data; }}class CircularlinkedList { private ListNode head = null; private int numberOfElements = 0; private ListNode actualElement = null; private int index = 0; public boolean isEmpty() { return (numberOfElements == 0); } public int getNumberOfElements() { return numberOfElements; } public void insertFirst(Object data) { if (!(isEmpty())) { index++; } ListNode listNode = new ListNode(data, head); head = listNode; numberOfElements++; } public void insertAfterActual(Object data) { ListNode listNode = new ListNode(data, actualElement.next); actualElement.next = listNode; numberOfElements++; } public boolean deleteFirst() { if (isEmpty()) return false; if (index > 0) index--; head = head.next; numberOfElements--; return true; } public boolean deleteActualElement() { if (index > 0) { numberOfElements--; index--; ListNode listNode = head; while (listNode.next.equals(actualElement) == false) listNode = listNode.next; listNode.next = actualElement.next; actualElement = listNode; return true; } else { actualElement = head.next; index = 0; return deleteFirst(); } } public boolean goTonextElement() { if (isEmpty()) return false; index = (index + 1) % numberOfElements; if (index == 0) actualElement = head; else actualElement = actualElement.next; return true; } public Object getActualElementData() { return actualElement.data; } public void setActualElementData(Object data) { actualElement.data = data; }}
