Object o1 = p1.toArray() line transforms all the PriorityQueue elements into the sorted array type.A Queue is an interface, which means you cannot construct a Queue directly.It returns true if value is present in p1, else returns boolean false value. boolean b=p1.contains(2) line checks whether specified element 2 is present in the PriorityQueue p1 or not and returns boolean true or false depending on the existence of element in p1.p1.offer (50) line adds the new specified element into the PriorityQueue p1.Integer head1=p1.peek () line points to the peek value of PriorityQueue p1 and stores the peek element into variable head.Integer head=p1.poll () line points to the poll value of PriorityQueue p1 and stores the poll element into variable head.

Comparator c1 = p1.comparator() line creates the instance c1 for comparator.(“Size of the Priority queue is: “+ p1.size ()) statement returns the size of the PriorityQueue p1 and displays the result on the output screen.p1.add (0) line adds the specified element to the PriorityQueue p1.PriorityQueue p1 = new PriorityQueue () line creates the PriorityQueue instance p1 by using the new operator.Hence, necessary to import when using comparator method. import this package includes the comparator functions.Above example illustrates the usage of methods add, poll, peek, size, toArray and comparator.( 'Priority queue after using offer is: '+ p1) ( 'peek of the Priority queue is: '+ head1) ( 'queue after Poll is applied on Priority queue is: '+ p1) ( 'Poll of the Priority queue is: '+ head) ( 'Size of the Priority queue is: '+ p1.size()) It returns the elements of the priority queue in the array type. It transforms the natural ordered queue to the ordered array queue. It returns the number of elements in the queue. It removes the defined object value from the queue. It point to the head of the queue, but does not remove it unlike the poll method does. It adds newly defined value to the existing queue.Īlong with indicating the head of the queue, it also removes the head of queue from the queue. To get the sorted order you need to call explicitly Arrays. This performs the iteration over the queue but does not guarantee the particular order of elements in the queue. If object exists in queue, it returns boolean true value or else returns false value. Make a check for the existence of the defined object in the queue. The comparator output is null value if ordering is done in accordance to their natural ordering. Ordering of elements in the queue is done after comparing the elements. It constructs a PriorityQueue for the elements given in the SortedSet.Īdds the specified element to the priority queue. It constructs a PriorityQueue for the elements given in the PriorityQueue. PriorityQueue is constructed with the given capacity which orders the elements according to the comparator. PriorityQueue (int initialCapacity, Comparator Comparator) PriorityQueue is constructed with the given capacity and ordering of elements is done in accordance with their natural ordering. It constructs a PriorityQueue for the elements given in the collection. Elements are ordered in their natural ordering. It constructs a default PriorityQueue with initial capacity of 11. PriorityQueue Class Constructors Constructor Where, E is the type of the element in the collection. Public class PriorityQueue extends AbstractQueue implements Serializable The size goes on increasing as we go on adding the elements to the queue. The size of PriorityQueue is unbounded, but it has the internal capacity to restrict its size according to the elements in the queue. Convert String to Date using SimpleDateFormat.Each element of the priority queue is assigned with a priority and thus the element with highest priority is always executed first. In natural ordering, elements are ordered and retrieved on the basis of “First in First out (FIFO)”, where as in PriorityQueue elements are retrieved on their priority basis. These are defined at the queue construction time which decides the ordering of elements in the queue, based on the type of constructor used. Comparator is the factor which compares the elements for the ordering purpose. In the PriorityQueue, elements are ordered in accordance to their natural ordering or the order defined by the Comparator.

Declare priority queue java