Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Ctors](https://developer.android.com/reference/java/util/PriorityQueue#pubctors) \| [Methods](https://developer.android.com/reference/java/util/PriorityQueue#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/PriorityQueue#inhmethods)

# PriorityQueue

` public class PriorityQueue `   
` ` ` ` ` extends https://developer.android.com/reference/java/util/AbstractQueue<E> ` ` implements https://developer.android.com/reference/java/io/Serializable `

|---|---|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||||
| ↳ | [java.util.AbstractCollection](https://developer.android.com/reference/java/util/AbstractCollection)\<E\> |||
|   | ↳ | [java.util.AbstractQueue](https://developer.android.com/reference/java/util/AbstractQueue)\<E\> ||
|   |   | ↳ | java.util.PriorityQueue\<E\> |

<br />

*** ** * ** ***

An unbounded priority [queue](https://developer.android.com/reference/java/util/Queue) based on a priority heap. The elements of the priority queue are ordered according to their [natural ordering](https://developer.android.com/reference/java/lang/Comparable), or by a `https://developer.android.com/reference/java/util/Comparator` provided at queue construction time, depending on which constructor is used. A priority queue does not permit `null` elements. A priority queue relying on natural ordering also does not permit insertion of non-comparable objects (doing so may result in `ClassCastException`).

The *head* of this queue is the *least* element with respect to the specified ordering. If multiple elements are tied for least value, the head is one of those elements -- ties are broken arbitrarily. The queue retrieval operations `poll`, `remove`, `peek`, and `element` access the element at the head of the queue.

A priority queue is unbounded, but has an internal *capacity* governing the size of an array used to store the elements on the queue. It is always at least as large as the queue size. As elements are added to a priority queue, its capacity grows automatically. The details of the growth policy are not specified.

This class and its iterator implement all of the *optional* methods of the `https://developer.android.com/reference/java/util/Collection` and `https://developer.android.com/reference/java/util/Iterator` interfaces. The Iterator provided in method `https://developer.android.com/reference/java/util/PriorityQueue#iterator()` and the Spliterator provided in method `https://developer.android.com/reference/java/util/PriorityQueue#spliterator()` are *not* guaranteed to traverse the elements of the priority queue in any particular order. If you need ordered traversal, consider using `Arrays.sort(pq.toArray())`.

**Note that this implementation is not synchronized.** Multiple threads should not access a `PriorityQueue` instance concurrently if any of the threads modifies the queue. Instead, use the thread-safe `https://developer.android.com/reference/java/util/concurrent/PriorityBlockingQueue` class.

Implementation note: this implementation provides O(log(n)) time for the enqueuing and dequeuing methods (`offer`, `poll`, `remove()` and `add`); linear time for the `remove(Object)` and `contains(Object)` methods; and constant time for the retrieval methods (`peek`, `element`, and `size`).

This class is a member of the [Java Collections Framework](https://reference/java/util/package-summary.html#CollectionsFramework).

## Summary

| ### Public constructors ||
|---|---|
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue()() ` Creates a `PriorityQueue` with the default initial capacity (11) that orders its elements according to their [natural ordering](https://developer.android.com/reference/java/lang/Comparable). |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(int)(int initialCapacity) ` Creates a `PriorityQueue` with the specified initial capacity that orders its elements according to their [natural ordering](https://developer.android.com/reference/java/lang/Comparable). |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(int,%20java.util.Comparator<?%20super%20E>)(int initialCapacity, https://developer.android.com/reference/java/util/Comparator<? super E> comparator) ` Creates a `PriorityQueue` with the specified initial capacity that orders its elements according to the specified comparator. |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(java.util.Collection<?%20extends%20E>)(https://developer.android.com/reference/java/util/Collection<? extends E> c) ` Creates a `PriorityQueue` containing the elements in the specified collection. |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(java.util.Comparator<?%20super%20E>)(https://developer.android.com/reference/java/util/Comparator<? super E> comparator) ` Creates a `PriorityQueue` with the default initial capacity and whose elements are ordered according to the specified comparator. |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(java.util.PriorityQueue<?%20extends%20E>)(https://developer.android.com/reference/java/util/PriorityQueue<? extends E> c) ` Creates a `PriorityQueue` containing the elements in the specified priority queue. |
| ` https://developer.android.com/reference/java/util/PriorityQueue#PriorityQueue(java.util.SortedSet<?%20extends%20E>)(https://developer.android.com/reference/java/util/SortedSet<? extends E> c) ` Creates a `PriorityQueue` containing the elements in the specified sorted set. |

| ### Public methods ||
|---|---|
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#add(E)(E e) ` Inserts the specified element into this priority queue. |
| ` void` | ` https://developer.android.com/reference/java/util/PriorityQueue#clear()() ` Removes all of the elements from this priority queue. |
| ` https://developer.android.com/reference/java/util/Comparator<? super E>` | ` https://developer.android.com/reference/java/util/PriorityQueue#comparator()() ` Returns the comparator used to order the elements in this queue, or `null` if this queue is sorted according to the [natural ordering](https://developer.android.com/reference/java/lang/Comparable) of its elements. |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#contains(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) ` Returns `true` if this queue contains the specified element. |
| ` void` | ` https://developer.android.com/reference/java/util/PriorityQueue#forEach(java.util.function.Consumer<?%20super%20E>)(https://developer.android.com/reference/java/util/function/Consumer<? super E> action) ` |
| ` https://developer.android.com/reference/java/util/Iterator<E>` | ` https://developer.android.com/reference/java/util/PriorityQueue#iterator()() ` Returns an iterator over the elements in this queue. |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#offer(E)(E e) ` Inserts the specified element into this priority queue. |
| ` E` | ` https://developer.android.com/reference/java/util/PriorityQueue#peek()() ` <br /> |
| ` E` | ` https://developer.android.com/reference/java/util/PriorityQueue#poll()() ` <br /> |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#remove(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) ` Removes a single instance of the specified element from this queue, if it is present. |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#removeAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) ` Removes all of this collection's elements that are also contained in the specified collection (optional operation). |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#removeIf(java.util.function.Predicate<?%20super%20E>)(https://developer.android.com/reference/java/util/function/Predicate<? super E> filter) ` |
| ` boolean` | ` https://developer.android.com/reference/java/util/PriorityQueue#retainAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) ` Retains only the elements in this collection that are contained in the specified collection (optional operation). |
| ` int` | ` https://developer.android.com/reference/java/util/PriorityQueue#size()() ` Returns the number of elements in this collection. |
| ` final https://developer.android.com/reference/java/util/Spliterator<E>` | ` https://developer.android.com/reference/java/util/PriorityQueue#spliterator()() ` Creates a *[late-binding](https://developer.android.com/reference/java/util/Spliterator#binding)* and *fail-fast* `https://developer.android.com/reference/java/util/Spliterator` over the elements in this queue. |
| ` <T> T[]` | ` https://developer.android.com/reference/java/util/PriorityQueue#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. |
| ` https://developer.android.com/reference/java/lang/Object` | ` https://developer.android.com/reference/java/util/PriorityQueue#toArray()() ` Returns an array containing all of the elements in this queue. |

### Inherited methods

From class ` https://developer.android.com/reference/java/util/AbstractQueue ` ` boolean` ` https://developer.android.com/reference/java/util/AbstractQueue#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` ` https://developer.android.com/reference/java/util/AbstractQueue#addAll(java.util.Collection<?%20extends%20E>)(https://developer.android.com/reference/java/util/Collection<? extends E> c) `

Adds all of the elements in the specified collection to this queue.
` void` ` https://developer.android.com/reference/java/util/AbstractQueue#clear()() `

Removes all of the elements from this queue.
` E` ` https://developer.android.com/reference/java/util/AbstractQueue#element()() `

Retrieves, but does not remove, the head of this queue.
` E` ` https://developer.android.com/reference/java/util/AbstractQueue#remove()() `

Retrieves and removes the head of this queue.
From class ` https://developer.android.com/reference/java/util/AbstractCollection ` ` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#add(E)(E e) `

Ensures that this collection contains the specified element (optional operation).
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#addAll(java.util.Collection<?%20extends%20E>)(https://developer.android.com/reference/java/util/Collection<? extends E> c) `

Adds all of the elements in the specified collection to this collection (optional operation).
` void` ` https://developer.android.com/reference/java/util/AbstractCollection#clear()() `

Removes all of the elements from this collection (optional operation).
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#contains(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) `

Returns `true` if this collection contains the specified element.
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#containsAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Returns `true` if this collection contains all of the elements in the specified collection.
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#isEmpty()() `

Returns `true` if this collection contains no elements.
` abstract https://developer.android.com/reference/java/util/Iterator<E>` ` https://developer.android.com/reference/java/util/AbstractCollection#iterator()() `

Returns an iterator over the elements contained in this collection.
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#remove(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) `

Removes a single instance of the specified element from this collection, if it is present (optional operation).
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#removeAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Removes all of this collection's elements that are also contained in the specified collection (optional operation).
` boolean` ` https://developer.android.com/reference/java/util/AbstractCollection#retainAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Retains only the elements in this collection that are contained in the specified collection (optional operation).
` abstract int` ` https://developer.android.com/reference/java/util/AbstractCollection#size()() `

Returns the number of elements in this collection.
` <T> T[]` ` https://developer.android.com/reference/java/util/AbstractCollection#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.
` https://developer.android.com/reference/java/lang/Object` ` https://developer.android.com/reference/java/util/AbstractCollection#toArray()() `

Returns an array containing all of the elements in this collection.
` https://developer.android.com/reference/java/lang/String` ` https://developer.android.com/reference/java/util/AbstractCollection#toString()() `

Returns a string representation of this collection.
From class ` https://developer.android.com/reference/java/lang/Object ` ` https://developer.android.com/reference/java/lang/Object` ` https://developer.android.com/reference/java/lang/Object#clone()() `

Creates and returns a copy of this object.
` boolean` ` https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj) `

Indicates whether some other object is "equal to" this one.
` void` ` https://developer.android.com/reference/java/lang/Object#finalize()() `

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
` final https://developer.android.com/reference/java/lang/Class<?>` ` https://developer.android.com/reference/java/lang/Object#getClass()() `

Returns the runtime class of this `Object`.
` int` ` https://developer.android.com/reference/java/lang/Object#hashCode()() `

Returns a hash code value for the object.
` final void` ` https://developer.android.com/reference/java/lang/Object#notify()() `

Wakes up a single thread that is waiting on this object's monitor.
` final void` ` https://developer.android.com/reference/java/lang/Object#notifyAll()() `

Wakes up all threads that are waiting on this object's monitor.
` https://developer.android.com/reference/java/lang/String` ` https://developer.android.com/reference/java/lang/Object#toString()() `

Returns a string representation of the object.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(long timeoutMillis, int nanos) `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait(long)(long timeoutMillis) `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait()() `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*.
From interface ` https://developer.android.com/reference/java/util/Queue ` ` abstract boolean` ` https://developer.android.com/reference/java/util/Queue#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` ` https://developer.android.com/reference/java/util/Queue#element()() `

Retrieves, but does not remove, the head of this queue.
` abstract boolean` ` https://developer.android.com/reference/java/util/Queue#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` ` https://developer.android.com/reference/java/util/Queue#peek()() `

Retrieves, but does not remove, the head of this queue, or returns `null` if this queue is empty.
` abstract E` ` https://developer.android.com/reference/java/util/Queue#poll()() `

Retrieves and removes the head of this queue, or returns `null` if this queue is empty.
` abstract E` ` https://developer.android.com/reference/java/util/Queue#remove()() `

Retrieves and removes the head of this queue.
From interface ` https://developer.android.com/reference/java/util/Collection ` ` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#add(E)(E e) `

Ensures that this collection contains the specified element (optional operation).
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#addAll(java.util.Collection<?%20extends%20E>)(https://developer.android.com/reference/java/util/Collection<? extends E> c) `

Adds all of the elements in the specified collection to this collection (optional operation).
` abstract void` ` https://developer.android.com/reference/java/util/Collection#clear()() `

Removes all of the elements from this collection (optional operation).
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#contains(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) `

Returns `true` if this collection contains the specified element.
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#containsAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Returns `true` if this collection contains all of the elements in the specified collection.
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) `

Compares the specified object with this collection for equality.
` abstract int` ` https://developer.android.com/reference/java/util/Collection#hashCode()() `

Returns the hash code value for this collection.
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#isEmpty()() `

Returns `true` if this collection contains no elements.
` abstract https://developer.android.com/reference/java/util/Iterator<E>` ` https://developer.android.com/reference/java/util/Collection#iterator()() `

Returns an iterator over the elements in this collection.
` default https://developer.android.com/reference/java/util/stream/Stream<E>` ` https://developer.android.com/reference/java/util/Collection#parallelStream()() `

Returns a possibly parallel `Stream` with this collection as its source.
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#remove(java.lang.Object)(https://developer.android.com/reference/java/lang/Object o) `

Removes a single instance of the specified element from this collection, if it is present (optional operation).
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#removeAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Removes all of this collection's elements that are also contained in the specified collection (optional operation).
` default boolean` ` https://developer.android.com/reference/java/util/Collection#removeIf(java.util.function.Predicate<?%20super%20E>)(https://developer.android.com/reference/java/util/function/Predicate<? super E> filter) `

Removes all of the elements of this collection that satisfy the given predicate (optional operation).
` abstract boolean` ` https://developer.android.com/reference/java/util/Collection#retainAll(java.util.Collection<?>)(https://developer.android.com/reference/java/util/Collection<?> c) `

Retains only the elements in this collection that are contained in the specified collection (optional operation).
` abstract int` ` https://developer.android.com/reference/java/util/Collection#size()() `

Returns the number of elements in this collection.
` default https://developer.android.com/reference/java/util/Spliterator<E>` ` https://developer.android.com/reference/java/util/Collection#spliterator()() `

Creates a `https://developer.android.com/reference/java/util/Spliterator` over the elements in this collection.
` default https://developer.android.com/reference/java/util/stream/Stream<E>` ` https://developer.android.com/reference/java/util/Collection#stream()() `

Returns a sequential `Stream` with this collection as its source.
` abstract <T> T[]` ` https://developer.android.com/reference/java/util/Collection#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 https://developer.android.com/reference/java/lang/Object` ` https://developer.android.com/reference/java/util/Collection#toArray()() `

Returns an array containing all of the elements in this collection.
` default <T> T[]` ` https://developer.android.com/reference/java/util/Collection#toArray(java.util.function.IntFunction<T[]>)(https://developer.android.com/reference/java/util/function/IntFunction<T[]> generator) `

Returns an array containing all of the elements in this collection, using the provided `generator` function to allocate the returned array.
From interface ` https://developer.android.com/reference/java/lang/Iterable ` ` default void` ` https://developer.android.com/reference/java/lang/Iterable#forEach(java.util.function.Consumer<?%20super%20T>)(https://developer.android.com/reference/java/util/function/Consumer<? super T> action) `

Performs the given action for each element of the `Iterable` until all elements have been processed or the action throws an exception.
` abstract https://developer.android.com/reference/java/util/Iterator<E>` ` https://developer.android.com/reference/java/lang/Iterable#iterator()() `

Returns an iterator over elements of type `T`.
` default https://developer.android.com/reference/java/util/Spliterator<E>` ` https://developer.android.com/reference/java/lang/Iterable#spliterator()() `

Creates a `https://developer.android.com/reference/java/util/Spliterator` over the elements described by this `Iterable`.

## Public constructors

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue ()
```

Creates a `PriorityQueue` with the default initial capacity (11) that orders its elements according to their [natural ordering](https://developer.android.com/reference/java/lang/Comparable).

<br />

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (int initialCapacity)
```

Creates a `PriorityQueue` with the specified initial capacity that orders its elements according to their [natural ordering](https://developer.android.com/reference/java/lang/Comparable).

<br />

| Parameters ||
|---|---|
| `initialCapacity` | `int`: the initial capacity for this priority queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if `initialCapacity` is less than 1 |

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (int initialCapacity, 
                Comparator<? super E> comparator)
```

Creates a `PriorityQueue` with the specified initial capacity that orders its elements according to the specified comparator.

<br />

| Parameters ||
|---|---|
| `initialCapacity` | `int`: the initial capacity for this priority queue <br /> |
| `comparator` | `Comparator`: the comparator that will be used to order this priority queue. If `null`, the [natural ordering](https://developer.android.com/reference/java/lang/Comparable) of the elements will be used. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if `initialCapacity` is less than 1 |

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (Collection<? extends E> c)
```

Creates a `PriorityQueue` containing the elements in the specified collection. If the specified collection is an instance of a `https://developer.android.com/reference/java/util/SortedSet` or is another `PriorityQueue`, this priority queue will be ordered according to the same ordering. Otherwise, this priority queue will be ordered according to the [natural ordering](https://developer.android.com/reference/java/lang/Comparable) of its elements.

<br />

| Parameters ||
|---|---|
| `c` | `Collection`: the collection whose elements are to be placed into this priority queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassCastException` | if elements of the specified collection cannot be compared to one another according to the priority queue's ordering |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified collection or any of its elements are null |

### PriorityQueue

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (Comparator<? super E> comparator)
```

Creates a `PriorityQueue` with the default initial capacity and whose elements are ordered according to the specified comparator.

<br />

| Parameters ||
|---|---|
| `comparator` | `Comparator`: the comparator that will be used to order this priority queue. If `null`, the [natural ordering](https://developer.android.com/reference/java/lang/Comparable) of the elements will be used. <br /> |

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (PriorityQueue<? extends E> c)
```

Creates a `PriorityQueue` containing the elements in the specified priority queue. This priority queue will be ordered according to the same ordering as the given priority queue.

<br />

| Parameters ||
|---|---|
| `c` | `PriorityQueue`: the priority queue whose elements are to be placed into this priority queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassCastException` | if elements of `c` cannot be compared to one another according to `c`'s ordering |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified priority queue or any of its elements are null |

### PriorityQueue

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public PriorityQueue (SortedSet<? extends E> c)
```

Creates a `PriorityQueue` containing the elements in the specified sorted set. This priority queue will be ordered according to the same ordering as the given sorted set.

<br />

| Parameters ||
|---|---|
| `c` | `SortedSet`: the sorted set whose elements are to be placed into this priority queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassCastException` | if elements of the specified sorted set cannot be compared to one another according to the sorted set's ordering |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified sorted set or any of its elements are null |

## Public methods

### add

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean add (E e)
```

Inserts the specified element into this priority queue.

<br />

| Parameters ||
|---|---|
| `e` | `E`: the element to add <br /> |

| Returns ||
|---|---|
| `boolean` | `true` (as specified by `https://developer.android.com/reference/java/util/Collection#add(E)`) <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassCastException` | if the specified element cannot be compared with elements currently in this priority queue according to the priority queue's ordering |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified element is null |

### clear

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public void clear ()
```

Removes all of the elements from this priority queue. The queue will be empty after this call returns.

<br />

### comparator

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Comparator<? super E> comparator ()
```

Returns the comparator used to order the elements in this queue, or `null` if this queue is sorted according to the [natural ordering](https://developer.android.com/reference/java/lang/Comparable) of its elements.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Comparator<? super E>` | the comparator used to order this queue, or `null` if this queue is sorted according to the natural ordering of its elements <br /> |

### contains

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean contains (Object o)
```

Returns `true` if this queue contains the specified element. More formally, returns `true` if and only if this queue contains at least one element `e` such that `o.equals(e)`.

<br />

| Parameters ||
|---|---|
| `o` | `Object`: object to be checked for containment in this queue <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this queue contains the specified element <br /> |

### forEach

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public void forEach (Consumer<? super E> action)
```

<br />

<br />

| Parameters ||
|---|---|
| `action` | `Consumer` <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` |   |

### iterator

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Iterator<E> iterator ()
```

Returns an iterator over the elements in this queue. The iterator does not return the elements in any particular order.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Iterator<E>` | an iterator over the elements in this queue <br /> |

### offer

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean offer (E e)
```

Inserts the specified element into this priority queue.

<br />

| Parameters ||
|---|---|
| `e` | `E` <br /> |

| Returns ||
|---|---|
| `boolean` | `true` (as specified by `https://developer.android.com/reference/java/util/Queue#offer(E)`) <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ClassCastException` | if the specified element cannot be compared with elements currently in this priority queue according to the priority queue's ordering |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified element is null |

### peek

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public E peek ()
```

<br />

<br />

| Returns ||
|---|---|
| `E` | <br /> |

### poll

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public E poll ()
```

<br />

<br />

| Returns ||
|---|---|
| `E` | <br /> |

### remove

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean remove (Object o)
```

Removes a single instance of the specified element from this queue, if it is present. More formally, removes an element `e` such that `o.equals(e)`, if this queue contains one or more such elements. Returns `true` if and only if this queue contained the specified element (or equivalently, if this queue changed as a result of the call).

<br />

| Parameters ||
|---|---|
| `o` | `Object`: element to be removed from this queue, if present <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this queue changed as a result of the call <br /> |

### removeAll

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean removeAll (Collection<?> c)
```

Removes all of this collection's elements that are also contained in the specified collection (optional operation). After this call returns, this collection will contain no elements in common with the specified collection.

<br />

| Parameters ||
|---|---|
| `c` | `Collection`: collection containing elements to be removed from this collection <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this collection changed as a result of the call <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` |   |

### removeIf

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean removeIf (Predicate<? super E> filter)
```

<br />

<br />

| Parameters ||
|---|---|
| `filter` | `Predicate` <br /> |

| Returns ||
|---|---|
| `boolean` | <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` |   |

### retainAll

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public boolean retainAll (Collection<?> c)
```

Retains only the elements in this collection that are contained in the specified collection (optional operation). In other words, removes from this collection all of its elements that are not contained in the specified collection.

<br />

| Parameters ||
|---|---|
| `c` | `Collection`: collection containing elements to be retained in this collection <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this collection changed as a result of the call <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` |   |

### size

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
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`.

<br />

| Returns ||
|---|---|
| `int` | the number of elements in this collection <br /> |

### spliterator

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Spliterator<E> spliterator ()
```

Creates a *[late-binding](https://developer.android.com/reference/java/util/Spliterator#binding)* and *fail-fast* `https://developer.android.com/reference/java/util/Spliterator` over the elements in this queue. The spliterator does not traverse elements in any particular order (the `https://developer.android.com/reference/java/util/Spliterator#ORDERED` characteristic is not reported).

The `Spliterator` reports `https://developer.android.com/reference/java/util/Spliterator#SIZED`, `https://developer.android.com/reference/java/util/Spliterator#SUBSIZED`, and `https://developer.android.com/reference/java/util/Spliterator#NONNULL`. Overriding implementations should document the reporting of additional characteristic values.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Spliterator<E>` | a `Spliterator` over the elements in this queue <br /> |

### toArray

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
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 the queue fits in the specified array with room to spare (i.e., the array has more elements than the queue), the element in the array immediately following the end of the collection is set to `null`.

Like the `https://developer.android.com/reference/java/util/PriorityQueue#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.

Suppose `x` is a queue known to contain only strings. The following code can be used to dump the queue into a newly allocated array of `String`:

     String[] y = x.toArray(new String[0]);

Note that `toArray(new Object[0])` is identical in function to `toArray()`.

<br />

<br />

| Parameters ||
|---|---|
| `a` | `T`: 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. <br /> |

| Returns ||
|---|---|
| `T[]` | an array containing all of the elements in this queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/ArrayStoreException` | if the runtime type of the specified array is not a supertype of the runtime type of every element in this queue |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the specified array is null |

### toArray

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public Object[] toArray ()
```

Returns an array containing all of the elements in this queue. The 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.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Object` | an array containing all of the elements in this queue <br /> |