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() method import java.util.concurrent.*;
import java.util.*;
// The DelayObject for DelayQueue // It must implement Delayed and // its getDelay() and compareTo() method class 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 Class public 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}]