package org.refcard.blog.councurrency.delayqueue;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

public class DelayQueueExample {

 public static void main(String[] args) {

  BlockingQueue<DelayedElement> blockingQueue = new DelayQueue<DelayedElement>();

  try {
   blockingQueue.put(new DelayedElement(4000, "Message with delay 4s"));
   blockingQueue.put(new DelayedElement(2000, "Message with delay 2s"));
   blockingQueue.put(new DelayedElement(9000, "Message with delay 9s"));
  } catch (InterruptedException ie) {
  }

  while (!blockingQueue.isEmpty()) {
   try {
    System.out.println(">>" + blockingQueue.take());
   } catch (InterruptedException ie) {
   }

  }

 }
}

class DelayedElement implements Delayed {

 private long duration = 0;
 private String message;

 public DelayedElement(long duration, String name) {
  this.duration = System.currentTimeMillis() + duration;
  this.message = name;
 }

 @Override
 public int compareTo(Delayed o) {

  return (int) (this.duration - ((DelayedElement) o).getDuration());
 }

 @Override
 /*
  * Expiration occurs when an element's getDelay(TimeUnit unit) method
  * returns a value less than or equal to zero.
  */
 public long getDelay(TimeUnit unit) {
  long diff = duration - System.currentTimeMillis();
  return unit.convert(diff, TimeUnit.MILLISECONDS);
 }

 public long getDuration() {
  return duration;
 }

 public void setDuration(long duration) {
  this.duration = duration;
 }

 public String getMessage() {
  return message;
 }

 public void setMessage(String message) {
  this.message = message;
 }

 @Override
 public String toString() {
  return "DelayedElement [duration=" + duration + ", message=" + message
    + "]";
 }

}