KeySetView

add

fun add(element: K): Boolean

Adds the specified key to this set view by mapping the key to the default mapped value in the backing map, if defined.

addAll

fun addAll(elements: Collection<K>): Boolean

Adds all of the elements in the specified collection to this set, as if by calling add on each one.

clear

fun clear(): Unit

Removes all of the elements from this view, by removing all the mappings from the map backing this view.

contains

fun contains(element: K): Boolean

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

containsAll

fun containsAll(elements: Collection<K>): Boolean

Returns true if this collection contains all of the elements in the specified collection.

equals

fun equals(other: Any?): Boolean

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

forEach

fun forEach(action: Consumer<in K>): Unit

Performs the given action for each element of the Iterable until all elements have been processed or the action throws an exception. Actions are performed in the order of iteration, if that order is specified. Exceptions thrown by the action are relayed to the caller.

The behavior of this method is unspecified if the action performs side-effects that modify the underlying source of elements, unless an overriding class has specified a concurrent modification policy.

getMap

fun getMap(): ConcurrentHashMap<K, V>

Returns the map backing this view.

getMappedValue

fun getMappedValue(): V?

Returns the default mapped value for additions, or null if additions are not supported.

hashCode

fun hashCode(): Int

Returns a hash code value for the object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

isEmpty

fun isEmpty(): Boolean

Returns true if this collection contains no elements.

iterator

fun iterator(): MutableIterator<K>

remove

fun remove(element: K): Boolean

Removes the key from this map view, by removing the key (and its corresponding value) from the backing map. This method does nothing if the key is not in the map.

removeAll

fun removeAll(elements: Collection<K>): Boolean

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.

retainAll

fun retainAll(elements: Collection<K>): Boolean

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.

spliterator

fun spliterator(): Spliterator<K>

Creates a Spliterator over the elements in this collection. Implementations should document characteristic values reported by the spliterator. Such characteristic values are not required to be reported if the spliterator reports Spliterator.SIZED and this collection contains no elements.

The default implementation should be overridden by subclasses that can return a more efficient spliterator. In order to preserve expected laziness behavior for the stream() and parallelStream() methods, spliterators should either have the characteristic of IMMUTABLE or CONCURRENT, or be late-binding. If none of these is practical, the overriding class should describe the spliterator's documented policy of binding and structural interference, and should override the stream() and parallelStream() methods to create streams using a Supplier of the spliterator, as in:

<code>Stream&lt;E&gt; s = StreamSupport.stream(() -&gt; spliterator(), spliteratorCharacteristics)
  </code>

These requirements ensure that streams produced by the stream() and parallelStream() methods will reflect the contents of the collection as of initiation of the terminal stream operation.

toArray

fun toArray(): Array<Any!>

Returns an array containing all of the elements in this collection. If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order. The returned array's runtime component type is Object.

The returned array will be "safe" in that no references to it are maintained by this collection. (In other words, this method must allocate a new array even if this collection is backed by an array). The caller is thus free to modify the returned array.

toArray

fun <T : Any!> toArray(a: Array<T>): Array<T>

Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array. If the collection 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 collection.

If this collection fits in the specified array with room to spare (i.e., the array has more elements than this collection), the element in the array immediately following the end of the collection is set to null. (This is useful in determining the length of this collection only if the caller knows that this collection does not contain any null elements.)

If this collection makes any guarantees as to what order its elements are returned by its iterator, this method must return the elements in the same order.

toString

fun toString(): String

Returns a string representation of this collection. The string representation consists of the string representations of the collection's elements in the order they are returned by its iterator, enclosed in square brackets ("[]"). Adjacent elements are separated by the characters ", " (comma and space). Elements are converted to strings as by String.valueOf(Object).

size

val size: Int

Returns the number of elements in this collection. If this collection contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.