Java PriorityQueue数据结构接口原理及用法

package test;
import java.util.PriorityQueue;
public class PriorityQueueTest1 {
 @SuppressWarnings("unchecked")
 public static void main(String[] args) {
 PriorityQueue queue = new PriorityQueue();
 queue.add("AAAAA"); // Add接受的参数是Obj，PriorityQueue使用integer String等基本的数据类型时，默认new时有参数，如果不写则是按照默认排序
 queue.add("BBBBB"); 
 queue.add("CCCCC"); 
 queue.add("DDDDD"); 
 
 System.out.println(queue.peek()); // 获取但不移除此队列的头
 System.out.println(queue.poll()); // 获取并移除此队列的头
 System.out.println(queue.poll());
 
 queue.offer("ZZZZZ"); // 将指定的元素插入此优先级队列
 
 System.out.println(queue.poll());
 System.out.println(queue.poll());
 System.out.println(queue.poll());
 
 System.out.println(queue.poll()); // 到这里已经没有元素，打印Null
 }
}

package test;
import java.util.Comparator;
import java.util.PriorityQueue;
@SuppressWarnings("unchecked")
public class PriorityQueueTest2 {
 private static PriorityQueue queue = new PriorityQueue(10,new Comparators());
 public static void main(String[] args) {
 QueueObject queueObject = new QueueObject();
 queueObject.setId(4);
 queueObject.setObject("AAAAA");
 queue.add(queueObject);
 QueueObject queueObject1 = new QueueObject();
 queueObject1.setId(1);
 queueObject1.setObject("BBBBB");
 queue.add(queueObject1);
 QueueObject queueObject2 = new QueueObject();
 queueObject2.setId(3);
 queueObject2.setObject("CCCCC");
 queue.add(queueObject2);
 
 System.out.println(((QueueObject)queue.poll()).getObject());
 System.out.println(((QueueObject)queue.poll()).getObject());
 System.out.println(((QueueObject)queue.poll()).getObject());
 }
}
class QueueObject {
  private int id;
  private Object object;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public Object getObject() {
    return object;
  }
  public void setObject(Object object) {
    this.object = object;
  }
}
@SuppressWarnings("unchecked")
class Comparators implements Comparator{
  public int compare(Object arg0, Object arg1) {
    int val1 = ((QueueObject)arg0).getId();
    int val2 = ((QueueObject)arg1).getId();
    return val1 < val2 ? 0 : 1;
  }
}