PriorityBlockingQueue comparator() method in Java (original) (raw)
Last Updated : 03 Apr, 2023
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
import java.util.concurrent.PriorityBlockingQueue;
import java.util.*;
public class GFG {
`` public static void main(String[] args)
`` throws InterruptedException
`` {
`` PriorityBlockingQueue<Integer> PrioQueue
`` = new PriorityBlockingQueue<Integer>();
`` PrioQueue.put( 45815616 );
`` PrioQueue.put( 4981561 );
`` PrioQueue.put( 4594591 );
`` PrioQueue.put( 9459156 );
`` String str = PrioQueue.toString();
`` Comparator comp = PrioQueue.comparator();
`` 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
import java.util.concurrent.PriorityBlockingQueue;
import java.util.*;
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
`` {
`` int capacityOfQueue = 5 ;
`` PriorityBlockingQueue<String> characters
`` = new PriorityBlockingQueue<String>(capacityOfQueue,
`` new COMPARING());
`` characters.add("Geeks");
`` characters.add("forGeeks");
`` characters.add("A computer portal");
`` Comparator comp = characters.comparator();
`` System.out.println("Comparator value is: " + comp);
`` if (comp == null )
`` System.out.println("PriorityBlockingQueue"
`` + "follows natural ordering");
`` else
`` System.out.println("PriorityBlockingQueue follows: "
`` + comp);
`` 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,