DelayQueue iterator() method in Java with Examples Last Updated : 12 May, 2021 Comments Improve Suggest changes Like Article Like Report The iterator() method of DelayQueue is used to return an iterator over all the elements in the DelayQueue. These elements can be expired or unexpired.Syntax: public Iterator iterator () Parameters: This method does not accept any parameter.Returns: This method returns an iterator over elements in this delayqueue.Below program to illustrate DelayQueue iterator() in Java:Example: Java // Java Program Demonstrate DelayQueue iterator() 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)); // Creating an iterator Iterator val = DQ.iterator(); // print the value after iterating DelayQueue System.out.println("The iterator values are: "); while (val.hasNext()) { System.out.println(val.next()); } } } Output: The iterator values are: { A, time=1545818784540} { B, time=1545818784541} { C, time=1545818784542} { D, time=1545818784543} Comment More infoAdvertise with us Next Article DelayQueue iterator() method in Java with Examples P ProgrammerAnvesh Follow Improve Article Tags : Java Java-Collections Java - util package Java-Functions java-DelayQueue +1 More Practice Tags : JavaJava-Collections Similar Reads BlockingDeque iterator() method in Java with examples The iterator() method of BlockingDeque returns an iterator over the elements in this deque in a proper sequence. The elements will be returned in order from first (head) to last (tail). The returned iterator is a "weakly consistent" iterator. Syntax: public Iterator iterator() Parameters: This metho 2 min read DelayQueue add() method in Java with Examples The add(E ele) method of DelayQueue class in Java is used to insert the given element into the delay queue and returns true if the element has been successfully inserted. Here, E refers to the type of elements maintained by this DelayQueue collection.Syntax: public boolean add(E ele) Parameters: Thi 2 min read DelayQueue take() method in Java with Examples 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 2 min read DelayQueue poll() method in Java with Examples The poll() method of DelayQueue is used to retrieve head of the DelayQueue. This method also removes the head from the DelayQueue. Thus when poll method is called, DelayQueue size is reduced by one.Syntax: public E poll () Parameters: This method does not accept any parameter.Returns: This method re 3 min read DelayQueue peek() method in Java with Examples The peek() method of DelayQueue is used to retrieve head of the DelayQueue, but does not remove it, as in case of poll() method where head is removed from the DelayQueue. Syntax: public E peek () Parameters: This method does not accept any parameter. Returns: This method returns the head of the Dela 3 min read Like