java PriorityQueue维护自然秩序吗？

Question

The elements of the priority queue are ordered according to their natural ordering, or by a Comparator provided at queue construction time, depending on which constructor is used.

但是，在下面的示例中，当我一次打印整个队列时，队列的元素以随机顺序打印。另一方面，如果我逐个轮询元素，它们将按自然顺序打印

有人能给我解释一下这种模棱两可的行为吗？还是我遗漏了什么

public class QueueExample {


    public static class Employee implements Comparable<Employee>{
        private int id;
        private String name;

        public Employee(int id, String name){
            this.id=id;
            this.name=name;
        }

        public String toString(){
            return "id:"+id+" name:"+name;
        }

        public int compareTo(Employee emp){
            return name.compareTo(emp.name);
        }

    }

    public static void main(String[] args) {


        Queue<Employee> priority=new PriorityQueue<Employee>();

        priority.add(new Employee(101, "Atlas"));
        priority.add(new Employee(102, "Ztlas"));
        priority.add(new Employee(101, "Ftlas"));
        priority.add(new Employee(101, "Ptlas"));

        System.out.println(priority);

        System.out.println(priority.poll());
        System.out.println(priority.poll());
        System.out.println(priority.poll());
        System.out.println(priority.poll());

    }

}

输出：

[id:101 name:Atlas, id:101 name:Ptlas, id:101 name:Ftlas, id:102 name:Ztlas]

id:101 name:Atlas

id:101 name:Ftlas

id:101 name:Ptlas

id:102 name:Ztlas

Answer 1

再往下一点the documentation它说：

The Iterator provided in method iterator() is not guaranteed to traverse the elements of the priority queue in any particular order.

由于AbstractCollection的toString（由PriorityQueue继承）以迭代顺序返回字符串，因此不会从中获得特定顺序