StackOverflow2013

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copied!<p>I've done some exercises in Java and now I'm stuck at such a problem - my list works incorrectly. I am sure that <code>remove</code> works incorrectly and maybe you can help me (with advice or code) to implement a circular <strong>singly</strong> linked list in a correct way. I am not sure whether other functions work properly, but I've tried to do my best.</p> <p>Here is my code:</p> <pre><code>import java.util.*; public class Node { private Object value; private Object nextValue; private Node next; public Node(int data) { this.value = data; this.next = null; } public Object getValue() { return this.value; } public Node nextItem() { return this.next; } public void setNextItem(Node nextItem) { this.next = (Node) nextItem; this.next.setValue(nextItem.getValue()); } public void setValue(Object arg0) { this.value = arg0; } } ------------------------------------------------------------------- import java.util.*; public class CircularList { private Object[] array; private int arrSize; private int index; private Node head; private Node tail; public CircularList() { head = null; tail = null; } public boolean add(Node item) { if (item == null) { throw new NullPointerException("the item is null!!!"); } if (head == null) { head = item; head.setNextItem(head); arrSize++; return true; } Node cur = head; while(cur.nextItem() != head) { if(cur.getValue() == item.getValue()) { throw new IllegalArgumentException("the element already " + "exists!"); } cur = cur.nextItem(); } head.setNextItem(item); item.setNextItem(head); arrSize++; return true; } public Node getFirst() { return head; } public void insertAfter(Node item, Node nextItem) { if ((item == null) || (nextItem == null)) { throw new NullPointerException("the item is nul!!!"); } else if (this.contains(nextItem) == true) { throw new IllegalArgumentException("the item already exists!"); } Node cur = head; while(cur.nextItem() != head) { if(cur.getValue() == item.getValue()) { nextItem.setNextItem(item.nextItem()); item.setNextItem(nextItem); } else { cur = cur.nextItem(); } } } public boolean remove(Node item) { if(item == head) { Node cur = head; for(int i = 0; i < arrSize-1; i++) { cur = cur.nextItem(); } head = head.nextItem(); for(int i = 0; i < arrSize; i++) { cur = cur.nextItem(); } arrSize--; return true; } Node cur = head; int counter = 0; while(cur.nextItem() != head) { if(cur == item) { item = null; cur = cur.nextItem(); while(cur.nextItem() != head) { cur.setNextItem(cur.nextItem().nextItem()); } return true; } cur = cur.nextItem(); } return false; } public int size() { return arrSize; } public boolean contains(Object o) { if ((o == null) && (arrSize == 0)) { return false; } Node cur = head; while(cur.nextItem() != head) { if(cur.getValue() == o) { return true; } cur = cur.nextItem(); } return false; } } </code></pre>

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