# DelayQueue public class **DelayQueue** extends [AbstractQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html)\ implements [BlockingQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html)\ An unbounded {@linkplain BlockingQueue blocking queue} of `Delayed` elements, in which an element can only be taken when its delay has expired. The *head* of the queue is that `Delayed` element whose delay expired furthest in the past. If no delay has expired there is no head and `poll` will return `null`. Expiration occurs when an element's `getDelay(TimeUnit.NANOSECONDS)` method returns a value less than or equal to zero. Even though unexpired elements cannot be removed using `take` or `poll`, they are otherwise treated as normal elements. For example, the `size` method returns the count of both expired and unexpired elements. This queue does not permit null elements. This class and its iterator implement all of the *optional* methods of the `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html` and `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html` interfaces. The Iterator provided in method `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#iterator()` is *not* guaranteed to traverse the elements of the DelayQueue in any particular order. ### Public Constructor Summary |---|---| | | [DelayQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#DelayQueue())() Creates a new `DelayQueue` that is initially empty. | | | [DelayQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#DelayQueue(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Creates a `DelayQueue` initially containing the elements of the given collection of `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/Delayed.html` instances. | ### Public Method Summary |---|---| | boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#add(E))(E e) Inserts the specified element into this delay queue. | | void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#clear())() Atomically removes all of the elements from this delay queue. | | int | [drainTo](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#drainTo(java.util.Collection,%20int))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c, int maxElements) Removes at most the given number of available elements from this queue and adds them to the given collection. | | int | [drainTo](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#drainTo(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Removes all available elements from this queue and adds them to the given collection. | | [Iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html)\ | [iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#iterator())() Returns an iterator over all the elements (both expired and unexpired) in this queue. | | boolean | [offer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#offer(E))(E e) Inserts the specified element into this delay queue. | | boolean | [offer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#offer(E,%20long,%20java.util.concurrent.TimeUnit))(E e, long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Inserts the specified element into this delay queue. | | E | [peek](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#peek())() Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty. | | E | [poll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#poll(long,%20java.util.concurrent.TimeUnit))(long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue, or the specified wait time expires. | | E | [poll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#poll())() Retrieves and removes the head of this queue, or returns `null` if this queue has no elements with an expired delay. | | void | [put](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#put(E))(E e) Inserts the specified element into this delay queue. | | int | [remainingCapacity](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#remainingCapacity())() Always returns `Integer.MAX_VALUE` because a `DelayQueue` is not capacity constrained. | | boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Removes a single instance of the specified element from this queue, if it is present, whether or not it has expired. | | int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#size())() Returns the number of elements in this collection. | | E | [take](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#take())() Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue. | | \ T\[\] | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#toArray(T[]))(T\[\] a) Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. | | [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#toArray())() Returns an array containing all of the elements in this queue. | ### Inherited Method Summary From class [java.util.AbstractQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html) |---|---| | boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html#add(E))(E e) Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and throwing an `IllegalStateException` if no space is currently available. | | boolean | [addAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html#addAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Adds all of the elements in the specified collection to this queue. | | void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html#clear())() Removes all of the elements from this queue. | | E | [element](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html#element())() Retrieves, but does not remove, the head of this queue. | | E | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractQueue.html#remove())() Retrieves and removes the head of this queue. | From class [java.util.AbstractCollection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html) |---|---| | boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#add(E))(E e) Ensures that this collection contains the specified element (optional operation). This implementation always throws an UnsupportedOperationException. | | boolean | [addAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#addAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Adds all of the elements in the specified collection to this collection (optional operation). This implementation iterates over the specified collection, and adds each object returned by the iterator to this collection, in turn. | | void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#clear())() Removes all of the elements from this collection (optional operation). This implementation iterates over this collection, removing each element using the Iterator.remove operation. | | boolean | [contains](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#contains(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Returns true if this collection contains the specified element. This implementation iterates over the elements in the collection, checking each element in turn for equality with the specified element. | | boolean | [containsAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#containsAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Returns true if this collection contains all of the elements in the specified collection. This implementation iterates over the specified collection, checking each element returned by the iterator in turn to see if it's contained in this collection. | | boolean | [isEmpty](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#isEmpty())() Returns true if this collection contains no elements. This implementation returns size() == 0. | | abstract [Iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html)\ | [iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#iterator())() Returns an iterator over the elements contained in this collection. | | boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Removes a single instance of the specified element from this collection, if it is present (optional operation). This implementation iterates over the collection looking for the specified element. | | boolean | [removeAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#removeAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Removes all of this collection's elements that are also contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection. | | boolean | [retainAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#retainAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Retains only the elements in this collection that are contained in the specified collection (optional operation). This implementation iterates over this collection, checking each element returned by the iterator in turn to see if it's contained in the specified collection. | | abstract int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#size())() Returns the number of elements in this collection. | | \ T\[\] | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#toArray(T[]))(T\[\] contents) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. This implementation returns an array containing all the elements returned by this collection's iterator in the same order, stored in consecutive elements of the array, starting with index `0`. | | [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#toArray())() Returns an array containing all of the elements in this collection. This implementation returns an array containing all the elements returned by this collection's iterator, in the same order, stored in consecutive elements of the array, starting with index `0`. | | [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/AbstractCollection.html#toString())() Returns a string representation of this collection. | From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) |---|---| | [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. | | boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. | | void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. | | final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\ | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. | | int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. | | final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. | | final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. | | [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. | | final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. | | final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. | | final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. | From interface [java.util.Queue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html) |---|---| | abstract boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#add(E))(E e) Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and throwing an `IllegalStateException` if no space is currently available. | | abstract E | [element](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#element())() Retrieves, but does not remove, the head of this queue. | | abstract boolean | [offer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#offer(E))(E e) Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions. | | abstract E | [peek](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#peek())() Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty. | | abstract E | [poll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#poll())() Retrieves and removes the head of this queue, or returns `null` if this queue is empty. | | abstract E | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Queue.html#remove())() Retrieves and removes the head of this queue. | From interface [java.util.Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html) |---|---| | abstract boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#add(E))(E e) Ensures that this collection contains the specified element (optional operation). | | abstract boolean | [addAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#addAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Adds all of the elements in the specified collection to this collection (optional operation). | | abstract void | [clear](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#clear())() Removes all of the elements from this collection (optional operation). | | abstract boolean | [contains](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#contains(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Returns true if this collection contains the specified element. | | abstract boolean | [containsAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#containsAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Returns true if this collection contains all of the elements in the specified collection. | | abstract boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Compares the specified object with this collection for equality. | | abstract int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#hashCode())() Returns the hash code value for this collection. | | abstract boolean | [isEmpty](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#isEmpty())() Returns true if this collection contains no elements. | | abstract [Iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html)\ | [iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#iterator())() Returns an iterator over the elements in this collection. | | [Stream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/stream/Stream.html)\ | [parallelStream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#parallelStream())() Returns a possibly parallel `Stream` with this collection as its source. | | abstract boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Removes a single instance of the specified element from this collection, if it is present (optional operation). | | abstract boolean | [removeAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#removeAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Removes all of this collection's elements that are also contained in the specified collection (optional operation). | | boolean | [removeIf](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#removeIf(java.util.function.Predicate))([Predicate](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Predicate.html)\ filter) Removes all of the elements of this collection that satisfy the given predicate. | | abstract boolean | [retainAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#retainAll(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Retains only the elements in this collection that are contained in the specified collection (optional operation). | | abstract int | [size](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#size())() Returns the number of elements in this collection. | | [Spliterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html)\ | [spliterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#spliterator())() Creates a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html` over the elements in this collection. | | [Stream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/stream/Stream.html)\ | [stream](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#stream())() Returns a sequential `Stream` with this collection as its source. | | abstract \ T\[\] | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#toArray(T[]))(T\[\] a) Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. | | abstract [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [toArray](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#toArray())() Returns an array containing all of the elements in this collection. | From interface [java.util.concurrent.BlockingQueue](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html) |---|---| | abstract boolean | [add](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#add(E))(E e) Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and throwing an `IllegalStateException` if no space is currently available. | | abstract boolean | [contains](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#contains(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Returns `true` if this queue contains the specified element. | | abstract int | [drainTo](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#drainTo(java.util.Collection))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Removes all available elements from this queue and adds them to the given collection. | | abstract int | [drainTo](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#drainTo(java.util.Collection,%20int))([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c, int maxElements) Removes at most the given number of available elements from this queue and adds them to the given collection. | | abstract boolean | [offer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#offer(E))(E e) Inserts the specified element into this queue if it is possible to do so immediately without violating capacity restrictions, returning `true` upon success and `false` if no space is currently available. | | abstract boolean | [offer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#offer(E,%20long,%20java.util.concurrent.TimeUnit))(E e, long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Inserts the specified element into this queue, waiting up to the specified wait time if necessary for space to become available. | | abstract E | [poll](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#poll(long,%20java.util.concurrent.TimeUnit))(long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Retrieves and removes the head of this queue, waiting up to the specified wait time if necessary for an element to become available. | | abstract void | [put](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#put(E))(E e) Inserts the specified element into this queue, waiting if necessary for space to become available. | | abstract int | [remainingCapacity](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#remainingCapacity())() Returns the number of additional elements that this queue can ideally (in the absence of memory or resource constraints) accept without blocking, or `Integer.MAX_VALUE` if there is no intrinsic limit. | | abstract boolean | [remove](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#remove(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Removes a single instance of the specified element from this queue, if it is present. | | abstract E | [take](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/BlockingQueue.html#take())() Retrieves and removes the head of this queue, waiting if necessary until an element becomes available. | From interface [java.lang.Iterable](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Iterable.html) |---|---| | void | [forEach](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Iterable.html#forEach(java.util.function.Consumer))([Consumer](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/function/Consumer.html)\ action) Performs the given action for each element of the `Iterable` until all elements have been processed or the action throws an exception. | | abstract [Iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html)\ | [iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Iterable.html#iterator())() Returns an iterator over elements of type `T`. | | [Spliterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html)\ | [spliterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Iterable.html#spliterator())() Creates a `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Spliterator.html` over the elements described by this `Iterable`. | ## Public Constructors #### public **DelayQueue** () Creates a new `DelayQueue` that is initially empty. #### public **DelayQueue** ([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Creates a `DelayQueue` initially containing the elements of the given collection of `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/Delayed.html` instances. ##### Parameters | c | the collection of elements to initially contain | |---|---| ##### Throws | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified collection or any of its elements are null | |---|---| ## Public Methods #### public boolean **add** (E e) Inserts the specified element into this delay queue. ##### Parameters | e | the element to add | |---|---| ##### Returns - `true` (as specified by `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html#add(E)`) ##### Throws | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified element is null | |---|---| #### public void **clear** () Atomically removes all of the elements from this delay queue. The queue will be empty after this call returns. Elements with an unexpired delay are not waited for; they are simply discarded from the queue. #### public int **drainTo** ([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c, int maxElements) Removes at most the given number of available elements from this queue and adds them to the given collection. A failure encountered while attempting to add elements to collection `c` may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in `IllegalArgumentException`. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress. ##### Parameters | c | the collection to transfer elements into | | maxElements | the maximum number of elements to transfer | |---|---| ##### Returns - the number of elements transferred ##### Throws | [UnsupportedOperationException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/UnsupportedOperationException.html) | | | [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | | | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | | | [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | | |---|---| #### public int **drainTo** ([Collection](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Collection.html)\ c) Removes all available elements from this queue and adds them to the given collection. This operation may be more efficient than repeatedly polling this queue. A failure encountered while attempting to add elements to collection `c` may result in elements being in neither, either or both collections when the associated exception is thrown. Attempts to drain a queue to itself result in `IllegalArgumentException`. Further, the behavior of this operation is undefined if the specified collection is modified while the operation is in progress. ##### Parameters | c | the collection to transfer elements into | |---|---| ##### Returns - the number of elements transferred ##### Throws | [UnsupportedOperationException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/UnsupportedOperationException.html) | | | [ClassCastException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ClassCastException.html) | | | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | | | [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | | |---|---| #### public [Iterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Iterator.html)\ **iterator** () Returns an iterator over all the elements (both expired and unexpired) in this queue. The iterator does not return the elements in any particular order. The returned iterator is [*weakly consistent*](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/package-summary#Weakly). ##### Returns - an iterator over the elements in this queue #### public boolean **offer** (E e) Inserts the specified element into this delay queue. ##### Parameters | e | the element to add | |---|---| ##### Returns - `true` ##### Throws | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified element is null | |---|---| #### public boolean **offer** (E e, long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Inserts the specified element into this delay queue. As the queue is unbounded this method will never block. ##### Parameters | e | the element to add | | timeout | This parameter is ignored as the method never blocks | | unit | This parameter is ignored as the method never blocks | |---|---| ##### Returns - `true` ##### Throws | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | | |---|---| #### public E **peek** () Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty. Unlike `poll`, if no expired elements are available in the queue, this method returns the element that will expire next, if one exists. ##### Returns - the head of this queue, or `null` if this queue is empty #### public E **poll** (long timeout, [TimeUnit](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/TimeUnit.html) unit) Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue, or the specified wait time expires. ##### Parameters | timeout | how long to wait before giving up, in units of `unit` | | unit | a `TimeUnit` determining how to interpret the `timeout` parameter | |---|---| ##### Returns - the head of this queue, or `null` if the specified waiting time elapses before an element with an expired delay becomes available ##### Throws | [InterruptedException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/InterruptedException.html) | | |---|---| #### public E **poll** () Retrieves and removes the head of this queue, or returns `null` if this queue has no elements with an expired delay. ##### Returns - the head of this queue, or `null` if this queue has no elements with an expired delay #### public void **put** (E e) Inserts the specified element into this delay queue. As the queue is unbounded this method will never block. ##### Parameters | e | the element to add | |---|---| ##### Throws | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | | |---|---| #### public int **remainingCapacity** () Always returns `Integer.MAX_VALUE` because a `DelayQueue` is not capacity constrained. ##### Returns - `Integer.MAX_VALUE` #### public boolean **remove** ([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) o) Removes a single instance of the specified element from this queue, if it is present, whether or not it has expired. ##### Parameters | o | element to be removed from this collection, if present | |---|---| ##### Returns - true if an element was removed as a result of this call #### public int **size** () Returns the number of elements in this collection. If this collection contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE. ##### Returns - the number of elements in this collection #### public E **take** () Retrieves and removes the head of this queue, waiting if necessary until an element with an expired delay is available on this queue. ##### Returns - the head of this queue ##### Throws | [InterruptedException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/InterruptedException.html) | | |---|---| #### public T\[\] **toArray** (T\[\] a) Returns an array containing all of the elements in this queue; the runtime type of the returned array is that of the specified array. The returned array elements are in no particular order. If the queue fits in the specified array, it is returned therein. Otherwise, a new array is allocated with the runtime type of the specified array and the size of this queue. If this queue fits in the specified array with room to spare (i.e., the array has more elements than this queue), the element in the array immediately following the end of the queue is set to `null`. Like the `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/concurrent/DelayQueue.html#toArray()` method, this method acts as bridge between array-based and collection-based APIs. Further, this method allows precise control over the runtime type of the output array, and may, under certain circumstances, be used to save allocation costs. The following code can be used to dump a delay queue into a newly allocated array of `Delayed`: Delayed[] a = q.toArray(new Delayed[0]); Note that `toArray(new Object[0])` is identical in function to `toArray()`.
##### Parameters | a | the array into which the elements of the queue are to be stored, if it is big enough; otherwise, a new array of the same runtime type is allocated for this purpose | |---|---| ##### Returns - an array containing all of the elements in this queue ##### Throws | [ArrayStoreException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ArrayStoreException.html) | if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue | | [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if the specified array is null | |---|---| #### public [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) **toArray** () Returns an array containing all of the elements in this queue. The returned array elements are in no particular order. The returned array will be "safe" in that no references to it are maintained by this queue. (In other words, this method must allocate a new array). The caller is thus free to modify the returned array. This method acts as bridge between array-based and collection-based APIs. ##### Returns - an array containing all of the elements in this queue