record Student(int id, String name, double cgpa) implements Comparable<Student> {
@Override
public int compareTo(Student other) {
// Compare CGPA in descending order
return switch (Double.compare(other.cgpa, this.cgpa)) {
case 0 -> // If CGPAs are equal, compare names
switch (this.name.compareTo(other.name)) {
case 0 -> // If names are equal, compare IDs
Integer.compare(this.id, other.id);
default -> this.name.compareTo(other.name);
                    };
default -> Double.compare(other.cgpa, this.cgpa);
        };
    }
} 

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

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

alternative

public class StudentGrade {
// Student record using Java 16+ record feature
public record Student(int id, String name, double cgpa) {}

public static void main(String[] args) {
        List<String> events = List.of(
"ENTER John 3.75 50",
"ENTER Mark 3.8 24",
"ENTER Shafaet 3.7 35",
"SERVED",
"SERVED",
"ENTER Samiha 3.85 36",
"SERVED",
"ENTER Ashley 3.9 42",
"ENTER Maria 3.6 46",
"ENTER Anik 3.95 49",
"ENTER Dan 3.95 50",
"SERVED"
);

        Priorities p = new Priorities();
        List<Student> students = p.getStudents(events);

        students.forEach(System.out::println);

    }

public static class Priorities {
public List<Student> getStudents(List<String> events) {

            Comparator<Student> studentComparator = Comparator
                    .comparingDouble(Student::cgpa).reversed()
                    .thenComparing(Student::name)
                    .thenComparingInt(Student::id);

            PriorityQueue<Student> pq = new PriorityQueue<>(studentComparator);

for (String event : events) {
if (event.startsWith("ENTER")) {
                    String[] parts = event.split("\\s+");
                    String name = parts[1];
double cgpa = Double.parseDouble(parts[2]);
int id = Integer.parseInt(parts[3]);
                    pq.offer(new Student(id, name, cgpa));
                } else if (event.equals("SERVED")) {
                    pq.poll();
                }
            }

return pq.stream().toList();

        }
    }
}

· reeSet does not allow duplicate elements. If you try to add an element that compares as equal to an existing one, it will not be added.

· PriorityQueue allows duplicates.