Collections: PriorityQueue orders by priority, not insertion

A PriorityQueue keeps the smallest element (by its comparator) at the head. Note that toString shows heap order, so drain it with poll to see sorted output.

Code

record Task(String name, int priority) {}
var pq = new PriorityQueue<Task>(Comparator.comparingInt(Task::priority));

pq.add(new Task("email", 5));
pq.add(new Task("outage", 1));
pq.add(new Task("report", 3));

while (!pq.isEmpty()) {
    Task t = pq.poll();
    System.out.println(t.priority() + " " + t.name());
}

Output

1 outage
3 report
5 email

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Published 2026-07-30