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DelayQueue take() method in Java with Examples

  • Last Updated : 12 May, 2021

The take() method of DelayQueue is used to retrieve head of the DelayQueue and also removes it. Thus, the size of the DelayQueue is reduced. This function waits if an element with expired delay is available on this queue. 
Syntax: 
 

public E take ()

Parameters: This method accepts no parameters.
Return Value: The function returns the head of the DelayQueue.
Exception: This method throws InterruptedException if interrupted while waiting.
Below programs illustrate the DelayQueue.take() method:
Program: 
 

Java




// Java Program Demonstrate DelayQueue take() 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));
        DQ.add(new DelayObject("C", 3));
        DQ.add(new DelayObject("D", 4));
 
        // print the size of DelayQueue
        System.out.println("Size of the DelayQueue: "
                           + DQ.size());
        // print queue
        System.out.println("DelayQueue: "
                           + DQ);
 
        // take() function will retrieve and remove the head of DelayQueue
        System.out.println("Head of the DelayQueue:"
                           + DQ.take());
        // print the size of DelayQueue
        System.out.println("Size of the DelayQueue: "
                           + DQ.size());
        // print queue
        System.out.println("DelayQueue: "
                           + DQ);
    }
}
Output: 
Size of the DelayQueue: 4
DelayQueue: [
{ A, time=1546842594283}, 
{ B, time=1546842594284}, 
{ C, time=1546842594285}, 
{ D, time=1546842594286}]
Head of the DelayQueue:
{ A, time=1546842594283}
Size of the DelayQueue: 3
DelayQueue: [
{ B, time=1546842594284}, 
{ D, time=1546842594286}, 
{ C, time=1546842594285}]

 

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