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<Integer> 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<Customer> customerPriorityQueue = new PriorityQueue<>( idComparator);
		addDataToQueue(customerPriorityQueue);
		pollDataFromQueue(customerPriorityQueue);
	}

	//匿名Comparator实现

	public static Comparator<Customer> idComparator = new Comparator<Customer>(){
		@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<Customer> 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<Customer> customerPriorityQueue) {
		while(true){
			Customer cust = customerPriorityQueue.poll();
			if(cust == null) break;
			System.out.println("Processing Customer with ID="+cust.getId());
		}
	}


}