PriorityBlockingQueue comparator() method in Java
Last Updated :
11 Jul, 2025
The comparator() method of PriorityBlockingQueue returns the comparator that can be used to order the elements in a PriorityBlockingQueue. The method returns null value if the queue follows the natural ordering pattern of the elements. Syntax:
public Comparator<? super E> comparator()
Returns: This method returns the comparator set used to order the elements of the set in a specific order. It returns a null value if the PriorityBlockingQueue follows the default or natural ordering pattern. Below programs illustrate comparator() method of PriorityBlockingQueue: Example 1: To demonstrate comparator() method on PriorityBlockingQueue which contains a list of integers.
Java
// Java Program Demonstrate comparator()
// method of PriorityBlockingQueue
import java.util.concurrent.PriorityBlockingQueue;
import java.util.*;
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// create object of PriorityBlockingQueue
PriorityBlockingQueue<Integer> PrioQueue
= new PriorityBlockingQueue<Integer>();
// Add numbers to PriorityBlockingQueue
PrioQueue.put(45815616);
PrioQueue.put(4981561);
PrioQueue.put(4594591);
PrioQueue.put(9459156);
// get String representation of PriorityBlockingQueue
String str = PrioQueue.toString();
// Creating a comparator using comparator()
Comparator comp = PrioQueue.comparator();
// Displaying the comparator values
System.out.println("Comparator value: " + comp);
if (comp == null)
System.out.println("PriorityBlockingQueue"
+ "follows natural ordering");
else
System.out.println("PriorityBlockingQueue follows"
+ comp);
}
}
Output:Comparator value: null
PriorityBlockingQueuefollows natural ordering
Example 2: To demonstrate comparator() method on PriorityBlockingQueue which contains a list of integers.
Java
// Java Program Demonstrate comparator()
// method of PriorityBlockingQueue
import java.util.concurrent.PriorityBlockingQueue;
import java.util.*;
// Comparator to compare Strings
class COMPARING implements Comparator<String> {
public int compare(String str1, String str2)
{
return str2.compareTo(str1);
}
}
public class GFG {
public static void main(String[] args)
throws InterruptedException
{
// define capacity of PriorityBlockingQueue
int capacityOfQueue = 5;
// create object of PriorityBlockingQueue
// by passing capacity and comparator class
// as parameters.
PriorityBlockingQueue<String> characters
= new PriorityBlockingQueue<String>(capacityOfQueue,
new COMPARING());
// Add Strings
characters.add("Geeks");
characters.add("forGeeks");
characters.add("A computer portal");
// Getting the comparator using comparator()
Comparator comp = characters.comparator();
// Displaying the comparator values
System.out.println("Comparator value is: " + comp);
if (comp == null)
System.out.println("PriorityBlockingQueue"
+ "follows natural ordering");
else
System.out.println("PriorityBlockingQueue follows: "
+ comp);
// display result
System.out.println("\nThe elements after custom Comparator");
for (String e : characters)
System.out.print(e + ", ");
}
}
Output:Comparator value is: COMPARING@28d93b30
PriorityBlockingQueue follows: COMPARING@28d93b30
The elements after custom Comparator
forGeeks, Geeks, A computer portal,
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/PriorityBlockingQueue.html#comparator--
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