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POJava Linked List Priority Queue
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copied!<p>The ordered linked list implementation</p> <p>Here is the code I have written for some reason it won't compile and asks for a main function. I had used a main function to test this, but I need the program with out it.</p> <pre><code>package data_structures; import java.util.Iterator; import java.util.NoSuchElementException; public class ListPriorityQueue<E> implements PriorityQueue<E> { private Node head; private int size; private class Node { private E value; private Node next; public Node(E value, Node next) { this.value = value; this.next = next; } } private class NodeIter implements Iterator<E> { private E[] arr; private int n; public NodeIter() { n = size; arr = (E[]) new Object[n]; Node p = head; for (int i = 0; i < n; ++i) { arr[i] = p.value; p = p.next; } } public boolean hasNext() { return n > 0; } public E next() { if (n == 0) throw new NoSuchElementException(); return arr[--n]; } public void remove() { throw new UnsupportedOperationException(); } } public ListPriorityQueue() { this.head = null; this.size = 0; } public boolean insert(E object) { if (isFull()) return false; if (head == null) { head = new Node(object, null); } else if (((Comparable<E>)object).compareTo(head.value) < 0) { head = new Node(object, head); } else { Node p = head; while (p.next != null && ((Comparable<E>)object).compareTo(p.next.value) >= 0) { p = p.next; //or equal to preserve FIFO on equal items } p.next = new Node(object, p.next); } ++size; return true; } public E remove() { if (isEmpty()) return null; E value = head.value; head = head.next; --size; return value; } public E peek() { if (isEmpty()) return null; return head.value; } public int size() { return size; } public boolean contains(E object) { Node p = head; while (p != null) { if (((Comparable<E>)object).compareTo(p.value) == 0) return true; p = p.next; } return false; } public Iterator<E> iterator() { if (isEmpty()) return null; return new NodeIter(); } public void clear() { head = null; size = 0; } public boolean isEmpty() { return size == 0; } public boolean isFull() { return size == DEFAULT_MAX_CAPACITY; } } </code></pre>

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