Question

我正在尝试根据自定义Comparators对优先级队列进行排序，但是会引发错误：

Line 11: error: no suitable method found for sort(Queue<Custom>,<anonymous Comparator<Custom>>)

优先级队列用于对自定义类对象进行排序；我正在尝试使用不同的比较器对优先级队列进行多次排序。

我试图执行的代码：

class Solution {
    public List<Integer> findClosestElements(int[] arr, int k, int x) {
        // insert elements to PQ by distance
        Queue<Custom> pq = new PriorityQueue<Custom>();
        for(int i=0; i< arr.length; i++){
            // should sort the elements by default compare method of custom class
            pq.offer(new Custom(Math.abs(x-arr[i]), arr[i], i));
        }
        // some operations
        Collections.sort(pq, new Comparator<Custom>(){
            public int compare(Custom a, Custom b){
                return a.index-b.index;
            }
         });
        // using the lambda just like Collections.sort(pq, (a,b) -> a.index-b.index); returns no suitable method available for sort(Queue<Custom>,(a,b)->a.i[...]index)
        List<Integer> ret = new ArrayList<Integer>(k);
        while(ret.size()!=k){
            ret.add(pq.poll().num);
        }
        return ret;
    }
}
class Custom implements Comparator<Custom>, Comparable<Custom>{
        public int dist=0, num, index;
        public Custom(int dist, int num, int index){
            this.dist = dist;
            this.num = num;
            this.index = index;
        } 
        public int compare(Custom a, Custom b){
            return b.dist-a.dist;
        }
        public int compareTo(Custom b){
            return b.dist-this.dist;
        }
    }

Answer 1

因为排序正在使用列表sort(List<T> list, Comparator<? super T> c)，但“队列”不是列表。

Java优先级队列的自定义比较器

1 个答案: