LISTS, STACKS, QUEUES, AND PRIORITY QUEUES - Introduction to Java Programming: Comprehensive Version - page 785

«interface»
java.util.Queue<E>

java.util.PriorityQueue<E>

+PriorityQueue()
+PriorityQueue(initialCapacity: int)

Creates a default priority queue with initial capacity 11.
Creates a default priority queue with the specified initial
capacity.
Creates a priority queue with the specified collection.

+PriorityQueue(c: Collection<? extends
E>)
+PriorityQueue(initialCapacity: int,
comparator: Comparator<? super E>)

Creates a priority queue with the specified initial
capacity and the comparator.

F IGURE 20.14

The PriorityQueue class implements a priority queue.

L ISTING 20.8

PriorityQueueDemo.java
1 import java.util.*;
2
3 public class PriorityQueueDemo {
4 public static void main(String[] args) {
5 PriorityQueue<String> queue1 = new PriorityQueue<>();
6 queue1.offer( "Oklahoma" );
7 queue1.offer( "Indiana" );
8 queue1.offer( "Georgia" );
9 queue1.offer( "Texas" );
10
11 System.out.println( "Priority queue using Comparable:" );
12 while (queue1.size() > 0 ) {
13 System.out.print(queue1.remove() + " " );
14 }
15
16 PriorityQueue<String> queue2 = new PriorityQueue(
17 4 , Collections.reverseOrder());
18 queue2.offer( "Oklahoma" );
19 queue2.offer( "Indiana" );
20 queue2.offer( "Georgia" );
21 queue2.offer( "Texas" );
22
23 System.out.println( "\nPriority queue using Comparator:" );
24 while (queue2.size() > 0 ) {
25 System.out.print(queue2.remove() + " " );
26 }
27 }
28 }

a default queue
inserts an element

a queue with comparator

Priority queue using Comparable:
Georgia Indiana Oklahoma Texas
Priority queue using Comparator:
Texas Oklahoma Indiana Georgia

20.29

✓ ✓

Is java.util.Queue a subinterface of java.util.Collection , java.util.Set ,
or java.util.List ? Does LinkedList implement Queue ?

Check

Point