The offer() method of DelayQueue is used to insert specified element in the delay queue. It acts similar to add() method of DelayQueue.
Syntax:
public boolean offer (E e)
Parameters:
DelayQueue accepts only those elements that belong to a class of type Delayed. So, this element E should be of type Delayed.
Returns:
This method does not return anything.
Exception:
Null pointer Exception: if the specified element is null.
Below program to illustrate DelayQueue offer() in Java:
Example:
Java
// Java Program Demonstrate DelayQueue offer() methodimport java.util.concurrent.*;import java.util.*;// The DelayObject for DelayQueue// It must implement Delayed and// its getDelay() and compareTo() methodclass DelayObject implements Delayed { private String name; private long time; // Constructor of DelayObject public DelayObject(String name, long delayTime) { this.name = name; this.time = System.currentTimeMillis() + delayTime; } // Implementing getDelay() method of Delayed @Override public long getDelay(TimeUnit unit) { long diff = time - System.currentTimeMillis(); return unit.convert(diff, TimeUnit.MILLISECONDS); } // Implementing compareTo() method of Delayed @Override public int compareTo(Delayed obj) { if (this.time < ((DelayObject)obj).time) { return -1; } if (this.time > ((DelayObject)obj).time) { return 1; } return 0; } // Implementing toString() method of Delayed @Override public String toString() { return "\n{" + " " + name + ", time=" + time + "}"; }}// Driver Classpublic class GFG { public static void main(String[] args) throws InterruptedException { // create object of DelayQueue // using DelayQueue() constructor BlockingQueue<DelayObject> DQ = new DelayQueue<DelayObject>(); // Add numbers to end of DelayQueue // using add() method DQ.add(new DelayObject("A", 1)); DQ.add(new DelayObject("B", 2)); // Print delayqueue System.out.println("Original DelayQueue: " + DQ + "\n"); // Now insert elements using offer method DQ.offer(new DelayObject("C", 10)); DQ.offer(new DelayObject("D", 11)); DQ.offer(new DelayObject("E", 15)); DQ.offer(new DelayObject("F", 17)); // print queue System.out.println("After insertion DelayQueue: " + DQ); }} |
Output:
Original DelayQueue: [
{ A, time=1545817395066},
{ B, time=1545817395067}]
After insertion DelayQueue: [
{ A, time=1545817395066},
{ B, time=1545817395067},
{ C, time=1545817395076},
{ D, time=1545817395077},
{ E, time=1545817395081},
{ F, time=1545817395083}]
