Program to Customize the Ordering of Elements in a PriorityQueue

Customize the Ordering of Elements in a PriorityQueue

Let’s create a PriorityQueue of students based on their CGPA (grade point average). We’ll define a custom comparator (StudentComparator) that compares students’ CGPA values

Below is the implementation of Customize the Ordering of Elements in a PriorityQueue:

Java

// Java Program to Customize the Ordering 
// of Elements in a PriorityQueue 
import java.util.*; 
  
// Class representing a priority queue of students 
public class GFG { 
    // Main method 
    public static void main(String[] args) { 
        // Create a scanner object for input 
        Scanner in = new Scanner(System.in); 
          
        // Create a priority queue of students with custom comparator 
        PriorityQueue<Student> pq = new PriorityQueue<>(5, new StudentComparator()); 
  
        // Create student objects and add them to the priority queue 
        Student student1 = new Student("Nandini", 3.2); 
        pq.add(student1); 
  
        Student student2 = new Student("Anmol", 3.6); 
        pq.add(student2); 
  
        Student student3 = new Student("Palak", 4.0); 
        pq.add(student3); 
  
        // Print the students served in their priority order 
        System.out.println("Students served in their priority order:"); 
        while (!pq.isEmpty()) { 
            System.out.println(pq.poll().getName()); 
        } 
    } 
} 
  
// Comparator class for comparing students based on their CGPA 
class StudentComparator implements Comparator<Student> { 
    // Compare method to compare two students 
    public int compare(Student s1, Student s2) { 
        if (s1.cgpa < s2.cgpa) return 1; 
        else if (s1.cgpa > s2.cgpa) return -1; 
        return 0; 
    } 
} 
  
// Class representing a student 
class Student { 
    // Member variables 
    public String name; 
    public double cgpa; 
  
    // Constructor 
    public Student(String name, double cgpa) { 
        this.name = name; 
        this.cgpa = cgpa; 
    } 
  
    // Method to get the name of the student 
    public String getName() { 
        return name; 
    } 
} 

Output

Students served in their priority order:
Palak
Anmol
Nandini

Explanation of the above Program:

In the example above, we create a priorityQueue of Students.
The custom comparator (StudentComparator) orders students based on their CGPA.
Students with higher CGPA are served first, demonstrating customized ordering.

Let’s explore another approach for customizing the ordering of elements in a PriorityQueue using a Comparator in java.

How to Customize the Ordering of Elements in a PriorityQueue Using a Comparator in Java?

A PriorityQueue is a data structure that allows elements to be processed based on their priority. By default, it orders elements according to their natural ordering (e.g., numeric values in ascending order). However, sometimes we need a different sorting order based on specific criteria.

In this article, we will learn to Customize the Ordering of Elements in a PriorityQueue Using a Comparator in Java.

Prerequisites:

Tags:

#Java Examples #Java-Collections #java-priority-queue #priority-queue #Java #Java Programs #Java #Java-Collections #priority-queue