import java.util.ArrayList; import java.util.List; import java.util.Scanner; import java.util.PriorityQueue;

class Student implements Comparable < Student > { private int id; private String name; private double cgpa;

public Student(int id, String name, double cgpa) {
    this.id = id;
    this.name = name;
    this.cgpa = cgpa;
}

@Override
public int compareTo(Student other) {
    if (this.cgpa != other.cgpa) {
        return Double.compare(other.cgpa, this.cgpa);
    } else if (!(this.name.equals(other.name))) {
        return this.name.compareTo(other.name);
    } else {
        return this.id - other.id;
    }
}

public int getID() {
    return id;
}

public String getName() {
    return name;
}

public double getCGPA() {
    return cgpa;
}

}

class Priorities { public List < Student > getStudents(List < String > events) { PriorityQueue < Student > queue = new PriorityQueue < > ();

    for (String each: events) {
        String[] arr = each.split(" ");
        String type = arr[0];

        if (type.equalsIgnoreCase("ENTER")) {
            String name = arr[1];
            double cgpa = Double.parseDouble(arr[2]);
            int id = Integer.parseInt(arr[3]);

            queue.add(new Student(id, name, cgpa));

        } else if (type.equalsIgnoreCase("SERVED")) {
            queue.poll();
        }
    }

    List < Student > students = new ArrayList < > ();

    while (!queue.isEmpty()) {
        students.add(queue.poll());
    }

    return students;
}

}

public class Solution { private final static Scanner scan = new Scanner(System.in); private final static Priorities priorities = new Priorities();

public static void main(String[] args) {
    int totalEvents = Integer.parseInt(scan.nextLine());
    List < String > events = new ArrayList < > ();

    while (totalEvents-- != 0) {
        String event = scan.nextLine();
        events.add(event);
    }

    List < Student > students = priorities.getStudents(events);

    if (students.isEmpty()) {
        System.out.println("EMPTY");
    } else {
        for (Student st: students) {
            System.out.println(st.getName());
        }
    }
}

}

Github Link: (https://github.com/OMWAGH9278/HackerRank/blob/main/Java/JavaPriorityQueue.java)

Here are the solution of Java Priority Queue HackerRank Solution

//here is code for java-8

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.PriorityQueue;
import java.util.Scanner;

class Student {
    private final int id;
    private final String name;
    private final double cgpa;

    public Student(int id, String name, double cgpa) {
        this.id = id;
        this.name = name;
        this.cgpa = cgpa;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public double getCgpa() {
        return cgpa;
    }
}

class Priorities {
    public List<Student> getStudents(List<String> events) {
        PriorityQueue<Student> queue = new PriorityQueue<>(
            Comparator.comparing(Student::getCgpa).reversed()
                .thenComparing(Student::getName)
                .thenComparing(Student::getId)
        );
        for (String event : events) {
            String[] parts = event.split("\\s+");
            if (parts[0].equals("ENTER")) {
                String name = parts[1];
                double cgpa = Double.parseDouble(parts[2]);
                int id = Integer.parseInt(parts[3]);
                Student student = new Student(id, name, cgpa);
                queue.add(student);
            } else if (parts[0].equals("SERVED")) {
                queue.poll();
            }
        }
        List<Student> students = new ArrayList<>(queue);
        students.sort(Comparator.comparing(Student::getCgpa).reversed()
            .thenComparing(Student::getName)
            .thenComparing(Student::getId)
        );
        return students;
    }
}

import java.util.PriorityQueue;

class Student implements Comparable { private int id; private String name; private double cgpa;

public Student(int id, String name, double cgpa) {
    this.id = id;
    this.name = name;
    this.cgpa = cgpa;
}

public int getId() {
    return id;
}

public String getName() {
    return name;
}

public double getCgpa() {
    return cgpa;
}

@Override
public int compareTo(Student other) {
    if (this.cgpa != other.cgpa) {
        return Double.compare(other.cgpa, this.cgpa);
    } else if (!this.name.equals(other.name)) {
        return this.name.compareTo(other.name);
    } else {
        return Integer.compare(this.id, other.id);
    }
}

}

class Priorities { public List getStudents(List events) { PriorityQueue queue = new PriorityQueue();

    for (String event : events) {
        String[] parts = event.split(" ");
        String type = parts[0];

        if (type.equals("ENTER")) {
            String name = parts[1];
            double cgpa = Double.parseDouble(parts[2]);
            int id = Integer.parseInt(parts[3]);
            queue.add(new Student(id, name, cgpa));
        } else if (type.equals("SERVED")) {
            queue.poll();
        }
    }

    List<Student> result = new ArrayList<Student>();

    while (!queue.isEmpty()) {
        result.add(queue.poll());
    }

    return result;
}

}