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DelayQueue clear() method in Java
  • Last Updated : 23 Dec, 2018
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The clear() method of DelayQueue in Java is used to remove all of the elements in the current DelayQueue object. The queue will be empty after this call is returned. The elements in the queue whose Delay does not have an Expiry are automatically discarded from the Queue.


public void clear()

Parameters: This method does not takes any parameter.

Return Value: This method does not returns any value.

Below program illustrate the above method:

// Java program to illustrate the clear() method
// of DelayQueue class
import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;
public class GFG {
    public static void main(String args[])
        // Create a DelayQueue instance
        DelayQueue<Delayed> queue = new DelayQueue<Delayed>();
        // Create an Object of type Delayed
        Delayed obj = new Delayed() {
            public long getDelay(TimeUnit unit)
                return 24; // some value is returned
            public int compareTo(Delayed o)
                if (o.getDelay(TimeUnit.DAYS) > 
                    return 1;
                else if (o.getDelay(TimeUnit.DAYS) == 
                    return 0;
                return -1;
        // Add the obj to the queue
        // Check if queue is empty
        System.out.println("Is queue empty() : "
                           + queue.isEmpty());
        // Remove all elements from queue
        // uing clear() method
        // Check if queue is empty
        System.out.println("Is queue empty after calling clear() : "
                           + queue.isEmpty());
Is queue empty() : false
Is queue empty after calling clear() : true

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