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com.xiaoleilu.hutool.collection.BoundedPriorityQueue Maven / Gradle / Ivy

package com.xiaoleilu.hutool.collection;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.PriorityQueue;

/**
 * 有界优先队列
* 按照给定的排序规则,排序元素,当队列满时,按照给定的排序规则淘汰末尾元素(去除末尾元素) * @author xiaoleilu * * @param 成员类型 */ public class BoundedPriorityQueue extends PriorityQueue{ private static final long serialVersionUID = 3794348988671694820L; //容量 private int capacity; private Comparator comparator; public BoundedPriorityQueue(int capacity) { this(capacity, null); } /** * 构造 * @param capacity 容量 * @param comparator 比较器 */ public BoundedPriorityQueue(int capacity, final Comparator comparator) { super(capacity, new Comparator(){ @Override public int compare(E o1, E o2) { int cResult = 0; if(comparator != null) { cResult = comparator.compare(o1, o2); }else { @SuppressWarnings("unchecked") Comparable o1c = (Comparable)o1; cResult = o1c.compareTo(o2); } return - cResult; } }); this.capacity = capacity; this.comparator = comparator; } /** * 加入元素,当队列满时,淘汰末尾元素 * @param e 元素 * @return 加入成功与否 */ @Override public boolean offer(E e) { if(size() >= capacity) { E head = peek(); if (this.comparator().compare(e, head) <= 0){ return true; } //当队列满时,就要淘汰顶端队列 poll(); } return super.offer(e); } /** * 添加多个元素
* 参数为集合的情况请使用{@link PriorityQueue#addAll} * @param c 元素数组 * @return 是否发生改变 */ public boolean addAll(E[] c) { return this.addAll(Arrays.asList(c)); } /** * @return 返回排序后的列表 */ public ArrayList toList() { final ArrayList list = new ArrayList(this); Collections.sort(list, comparator); return list; } @Override public Iterator iterator() { return toList().iterator(); } }




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