priority queues wrong output?

[Kev Kit]

In a problem from Hackerrank, this question baffled me. I believe it should work fine but my output does not reflect on the expected output...  Where have I gone wrong? (also I can only edit the code before the Solution class)

Example Input:

12
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

My Output:

Dan
Ashley
Maria
Shafaet

Expected Output(very close):

Dan
Ashley
Shafaet
Maria

My code:

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

class Student {
    int id;
    String name;
    double cgpa;
    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) {
        String[] words = new String[4];
        ArrayList<Student> studArrList = new ArrayList<Student>();
        
        
        PriorityQueue<Student> priorityQ = new PriorityQueue<Student>(12, new studComp()); //students sorted
        

        for(String item: events) {            
            words = item.split(" "); //instruction is words[0], name is words[1], cgpa is words[2], id is words[3]
            if(words[0].equals("ENTER")) {                               
                priorityQ.offer(new Student(Integer.parseInt(words[3]),words[1],Double.parseDouble(words[2]))); 
            } else {
                priorityQ.poll();
            }
        }
        
        for(Student aStudent: priorityQ) {
            studArrList.add(aStudent);
        }

        return studArrList;
            
        
        
    }
}
class studComp implements Comparator<Student> {
    int a, b, compare;
    double a2, b2;
    public int compare(Student one, Student two) {
       if(one.getCgpa()!=two.getCgpa()) {
           a2 = one.getCgpa();
           b2 = two.getCgpa();
           compare = a2 > b2 ? -1: a2 < b2 ? 1:0;
       } else if(!(one.getName().equals(two.getName()))) {
           compare = one.getName().compareTo(two.getName());
       } else {
           a  = one.getId();
           b = two.getId();
            compare = a < b ? -1: a > b ? 1: 0;
       }
       return compare;
    }  
}

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());
            }
        }
    }
}

       

[Stephan van Hulst]

Do you know how the enhanced for-loop works? You might want to look up the documentation of the applicable method of the PriorityQueue class.

[Kev Kit]

Stephan van Hulst wrote:Do you know how the enhanced for-loop works? You might want to look up the documentation of the applicable method of the PriorityQueue class.

They go through every element one by one each repeat? I've read somewhere that iterators/enhanced for loops don't respect any particular orders but when using for loops over ArrayLists, they check each element in order? Sorry about bothering  

[Stephan van Hulst]

Enhanced for-loops use the Iterator provided by the Iterable or array you're iterating over.

Check out the documentation of the iterator() method of the PriorityQueue class.