PriorityQueue(優先隊列)使用完整示例

PriorityQueue(優先隊列)使用完整示例

package cc.cv;

import java.util.Comparator;
import java.util.PriorityQueue;
/**
 * PriorityQueue(優先隊列)使用完整示例
 * 采用PriorityQueue時裡面的每個元素按照一定標准的優先級進行存儲.
 * 而這個優先級的標准我們可以用Comparator來自己定義.
 * 
 * 參考資料:
 * 1 http://blog.csdn.net/chengyingzhilian/article/details/8078032
 * 2 http://java-er.com/blog/java-priority-queue/
 * 3 http://blog.csdn.net/hantiannan/article/details/7623108
 *   Thank you very much
 * 
 */
public class PriorityQueueTest {
	private int initialCapacity=10;
	public static void main(String[] args) {
		PriorityQueueTest priorityQueueTest=new PriorityQueueTest();
		priorityQueueTest.test();
	}
	
	
	/**
	 * 將一群斑馬放入優先隊列PriorityQueue中.
	 * 既然是優先隊列PriorityQueue,那麼就有一個優先的標准.
	 * 在此就按照每個斑馬的身高優先將一群斑馬存在隊列中
	 */
	private void test(){
		PriorityQueue priorityQueue=new PriorityQueue(initialCapacity, new ZebraComparator());
		Zebra zebra1=new Zebra("a", 130);
		priorityQueue.add(zebra1);
		Zebra zebra2=new Zebra("b", 130);
		priorityQueue.add(zebra2);
		Zebra zebra3=new Zebra("c", 130);
		priorityQueue.add(zebra3);
		Zebra zebra4=new Zebra("d", 130);
		priorityQueue.add(zebra4);
		Zebra zebra5=new Zebra("a", 110);
		priorityQueue.add(zebra5);
		Zebra zebra6=new Zebra("c", 120);
		priorityQueue.add(zebra6);
		
		System.out.println("priorityQueue.size()="+priorityQueue.size());
		
		//每個元素依次出隊,便於測試
		while (!priorityQueue.isEmpty()){
		     System.out.println(priorityQueue.poll());
		}
		
		System.out.println("priorityQueue.size()="+priorityQueue.size());
		
	}
	

	//按照斑馬的身高進行排序,身高相同時再比較名字
	class ZebraComparator implements Comparator {
		@Override
		public int compare(Object arg0, Object arg1) {
			Zebra zebra0 = (Zebra) arg0;
			Zebra zebra1 = (Zebra) arg1;
			if (zebra0.getHeight() > zebra1.getHeight()) {
				return 1;
			}
			// 身高相同時再比較名字
			if (zebra0.getHeight() == zebra1.getHeight()) {
				return zebra0.getName().compareTo(zebra1.getName());
			}

			if (zebra0.getHeight() < zebra1.getHeight()) {
				return -1;
			}

			return 0;
		}

	}
	
	
	
	/**
	 * 動物園裡的大熊貓和斑馬還是很可愛的。
	 * 看大熊貓的話,成都熊貓基地很爽.
	 * 看斑馬的話,北京動物園不錯,裡面還有需要仰著脖子看的長頸鹿......
	 * 在這裡就用斑馬舉例吧,它有名字和身高這兩個屬性
	 */
	private class Zebra{
		private String name;
		private int height;
	
		public Zebra(String name, int height) {
			super();
			this.name = name;
			this.height = height;
		}

		public String getName() {
			return name;
		}
		public void setName(String name) {
			this.name = name;
		}
		public int getHeight() {
			return height;
		}
		public void setHeight(int height) {
			this.height = height;
		}

		@Override
		public String toString() {
			return "Zebra [name=" + name + ", height=" + height + "]";
		}
		
	}

}