PriorityQueue用法

PriorityQueue

PriorityQueue是优先队列，作用是保证每次取出的元素都是队列中权值最小的，这里涉及到了大小关系，元素大小的评判可以通过元素自身的自然顺序（使用默认的比较器），也可以通过构造时传入的比较器。

用法

package DP;

import java.util.Comparator;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;

class Customer {
private int id;
private String name;
public Customer(int i, String n){
this.id=i;
this.name=n;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
}
public class T {
public static void main(String[] args) {
//优先队列自然排序示例
Queue integerPriorityQueue = new PriorityQueue<>(7);
Random rand = new Random();
for(int i=0;i<7;i++){
integerPriorityQueue.add(new Integer(rand.nextInt(100)));
}
for(int i=0;i<7;i++){
Integer in = integerPriorityQueue.poll();
System.out.println("Processing Integer:"+in);
}
//优先队列使用示例
Queue customerPriorityQueue = new PriorityQueue<>( idComparator);
addDataToQueue(customerPriorityQueue);
pollDataFromQueue(customerPriorityQueue);
}

//匿名Comparator实现

public static Comparator idComparator = new Comparator(){
@Override
public int compare(Customer c1, Customer c2) {
return (int) (c1.getId() - c2.getId());
}

};
//用于往队列增加数据的通用方法

private static void addDataToQueue(Queue customerPriorityQueue) {
Random rand = new Random();
for(int i=0; i<7; i++){
int id = rand.nextInt(100);
customerPriorityQueue.add(new Customer(id, "Pankaj "+id));
}
}
//用于从队列取数据的通用方法
private static void pollDataFromQueue(Queue customerPriorityQueue) {
while(true){
Customer cust = customerPriorityQueue.poll();
if(cust == null) break;
System.out.println("Processing Customer with ID="+cust.getId());
}
}

}