如果集合中的任何对象发生了变异，以便它的键(在比较器中使用)发生了变化，PriorityQueue是否会自行堆砌? [英] Does PriorityQueue heapify itself if any object in the collection is mutated so that it's key(used in comparator) changes?

问题描述

我只想知道Java的 PriorityQueue 集合是否自动进行堆化，比较器中使用的任何键是否发生突变，或者我是否需要显式调用heapify来订购 binary树?我正在尝试将数据结构用于诸如设置之类的缓存中，该数据结构在被引用后应立即将集合中的对象移到头部.

I just want to know if Java's PriorityQueue collection automatically heapifies, if any of the keys used in the comparator is mutated, or do i need to explicitly call heapify, to order the binary tree ? I am experimenting with the data structure to use it in a cache like setting, where an object in the collection should be immediately moved to the head, as soon as it is referenced.

推荐答案

当队列本身发生变异的操作(即 offer ， poll)时，队列会自动 heapifying ，删除和 add .

The queue automatically heapifies on operations that mutates the queue itself, namely offer, poll, remove and add.

如果您对元素进行了突变，则必须将其删除并重新插入.优先级队列无法得知元素已更新.

If you mutate an element you have to remove and re-insert it. The priority queue has no way of knowing that an element has been updated.

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