kotlin-stdlib/kotlin.collections/MutableMap

MutableMap

expect interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.0

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

actual interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.1

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

actual interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.0

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

actual interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.3

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

actual interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.8

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

actual interface MutableMap<K, V> : Map<K, V> (source)

A modifiable collection that holds pairs of objects (keys and values) and supports efficiently retrieving the value corresponding to each key. Map keys are unique; the map holds only one value for each key.

Since Kotlin

1.8

Parameters

K

the type of map keys. The map is invariant in its key type.

V

the type of map values. The mutable map is invariant in its value type.

Inheritors

Types

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expect interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.0
actual interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.1
actual interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.0
actual interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.3
actual interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.8
actual interface MutableEntry<K, V> : Map.Entry<K, V>

Represents a key/value pair held by a MutableMap.

Since Kotlin 1.8

Properties

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expect abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.0
actual abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.1
actual abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.0
actual abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.3
actual abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.8
actual abstract override val entries: MutableSet<MutableMap.MutableEntry<K, V>>

Returns a MutableSet of all key/value pairs in this map.

Since Kotlin 1.8
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expect abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.0
actual abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.1
actual abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.0
actual abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.3
actual abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.8
actual abstract override val keys: MutableSet<K>

Returns a MutableSet of all keys in this map.

Since Kotlin 1.8
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expect abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.0
actual abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.1
actual abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.0
actual abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.3
actual abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.8
actual abstract val size: Int

Returns the number of key/value pairs in the map.

Since Kotlin 1.8
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expect abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.0
actual abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.1
actual abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.0
actual abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.3
actual abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.8
actual abstract override val values: MutableCollection<V>

Returns a MutableCollection of all values in this map. Note that this collection may contain duplicate values.

Since Kotlin 1.8

Functions

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inline fun <K, V> Map<out K, V>.all(predicate: (Map.Entry<K, V>) -> Boolean): Boolean

Returns true if all entries match the given predicate.

Since Kotlin 1.0
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fun <K, V> Map<out K, V>.any(): Boolean

Returns true if map has at least one entry.

Since Kotlin 1.0
inline fun <K, V> Map<out K, V>.any(predicate: (Map.Entry<K, V>) -> Boolean): Boolean

Returns true if at least one entry matches the given predicate.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.asIterable(): Iterable<Map.Entry<K, V>>

Creates an Iterable instance that wraps the original map returning its entries when being iterated.

Since Kotlin 1.0
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@ExperimentalJsExport
@ExperimentalJsCollectionsApi
open fun asJsMapView(): JsMap<K, V>

Returns a view with the JsMap methods to consume it in JavaScript as a regular Map. Structural changes in the base map are synchronized with the view, and vice verse.

Since Kotlin 2.0
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@ExperimentalJsExport
@ExperimentalJsCollectionsApi
open fun asJsReadonlyMapView(): JsReadonlyMap<K, V>

Returns a view with the JsReadonlyMap methods to consume it in JavaScript as a regular readonly Map. Structural changes in the base map are synchronized with the view.

Since Kotlin 2.0
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fun <K, V> Map<out K, V>.asSequence(): Sequence<Map.Entry<K, V>>

Creates a Sequence instance that wraps the original map returning its entries when being iterated.

Since Kotlin 1.0
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expect abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.0
actual abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.1
actual abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.0
actual abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.3
actual abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.8
actual abstract fun clear()

Removes all elements from this map.

Since Kotlin 1.8
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inline operator fun <K, V> Map<out K, V>.contains(key: K): Boolean

Checks if the map contains the given key.

Since Kotlin 1.0
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expect abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.0
actual abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.1
actual abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.0
actual abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.3
actual abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.8
actual abstract fun containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.8
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inline fun <K> Map<out K, *>.containsKey(key: K): Boolean

Returns true if the map contains the specified key.

Since Kotlin 1.0
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expect abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.0
actual abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.1
actual abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.0
actual abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.3
actual abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.8
actual abstract fun containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.8
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inline fun <K, V> Map<K, V>.containsValue(value: V): Boolean

Returns true if the map maps one or more keys to the specified value.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.count(): Int

Returns the number of entries in this map.

Since Kotlin 1.0
inline fun <K, V> Map<out K, V>.count(predicate: (Map.Entry<K, V>) -> Boolean): Int

Returns the number of entries matching the given predicate.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.filter(predicate: (Map.Entry<K, V>) -> Boolean): Map<K, V>

Returns a new map containing all key-value pairs matching the given predicate.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.filterKeys(predicate: (K) -> Boolean): Map<K, V>

Returns a map containing all key-value pairs with keys matching the given predicate.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.filterNot(predicate: (Map.Entry<K, V>) -> Boolean): Map<K, V>

Returns a new map containing all key-value pairs not matching the given predicate.

Since Kotlin 1.0
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inline fun <K, V, M : MutableMap<in K, in V>> Map<out K, V>.filterNotTo(destination: M, predicate: (Map.Entry<K, V>) -> Boolean): M

Appends all entries not matching the given predicate into the given destination.

Since Kotlin 1.0
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inline fun <K, V, M : MutableMap<in K, in V>> Map<out K, V>.filterTo(destination: M, predicate: (Map.Entry<K, V>) -> Boolean): M

Appends all entries matching the given predicate into the mutable map given as destination parameter.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.filterValues(predicate: (V) -> Boolean): Map<K, V>

Returns a map containing all key-value pairs with values matching the given predicate.

Since Kotlin 1.0
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inline fun <K, V, R : Any> Map<out K, V>.firstNotNullOf(transform: (Map.Entry<K, V>) -> R?): R

Returns the first non-null value produced by transform function being applied to entries of this map in iteration order, or throws NoSuchElementException if no non-null value was produced.

Since Kotlin 1.5
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inline fun <K, V, R : Any> Map<out K, V>.firstNotNullOfOrNull(transform: (Map.Entry<K, V>) -> R?): R?

Returns the first non-null value produced by transform function being applied to entries of this map in iteration order, or null if no non-null value was produced.

Since Kotlin 1.5
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inline fun <K, V, R> Map<out K, V>.flatMap(transform: (Map.Entry<K, V>) -> Iterable<R>): List<R>

Returns a single list of all elements yielded from results of transform function being invoked on each entry of original map.

Since Kotlin 1.0
@JvmName(name = "flatMapSequence")
inline fun <K, V, R> Map<out K, V>.flatMap(transform: (Map.Entry<K, V>) -> Sequence<R>): List<R>

Returns a single list of all elements yielded from results of transform function being invoked on each entry of original map.

Since Kotlin 1.4
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inline fun <K, V, R, C : MutableCollection<in R>> Map<out K, V>.flatMapTo(destination: C, transform: (Map.Entry<K, V>) -> Iterable<R>): C

Appends all elements yielded from results of transform function being invoked on each entry of original map, to the given destination.

Since Kotlin 1.0
@JvmName(name = "flatMapSequenceTo")
inline fun <K, V, R, C : MutableCollection<in R>> Map<out K, V>.flatMapTo(destination: C, transform: (Map.Entry<K, V>) -> Sequence<R>): C

Appends all elements yielded from results of transform function being invoked on each entry of original map, to the given destination.

Since Kotlin 1.4
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inline fun <K, V> Map<out K, V>.forEach(action: (Map.Entry<K, V>) -> Unit)

Performs the given action on each entry.

Since Kotlin 1.0
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expect abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.0
actual abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.1
actual abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.0
actual abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.3
actual abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.8
actual abstract operator fun get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.8
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inline operator fun <K, V> Map<out K, V>.get(key: K): V?

Returns the value corresponding to the given key, or null if such a key is not present in the map.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.getOrDefault(key: K, defaultValue: V): V

Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key.

Since Kotlin 1.2
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inline fun <K, V> Map<K, V>.getOrElse(key: K, defaultValue: () -> V): V

Returns the value for the given key if the value is present and not null. Otherwise, returns the result of the defaultValue function.

Since Kotlin 1.0
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inline fun <K, V> MutableMap<K, V>.getOrPut(key: K, defaultValue: () -> V): V

Returns the value for the given key if the value is present and not null. Otherwise, calls the defaultValue function, puts its result into the map under the given key and returns the call result.

Since Kotlin 1.0
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fun <K, V> Map<K, V>.getValue(key: K): V

Returns the value for the given key or throws an exception if there is no such key in the map.

Since Kotlin 1.1
inline operator fun <V, V1 : V> Map<in String, V>.getValue(thisRef: Any?, property: KProperty<*>): V1

Returns the value of the property for the given object from this read-only map.

Since Kotlin 1.0
@JvmName(name = "getVar")
inline operator fun <V, V1 : V> MutableMap<in String, out V>.getValue(thisRef: Any?, property: KProperty<*>): V1

Returns the value of the property for the given object from this mutable map.

Since Kotlin 1.0
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expect abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.0
actual abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.1
actual abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.0
actual abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.3
actual abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.8
actual abstract fun isEmpty(): Boolean

Returns true if the map is empty (contains no elements), false otherwise.

Since Kotlin 1.8
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inline fun <K, V> Map<out K, V>.isNotEmpty(): Boolean

Returns true if this map is not empty.

Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>?.isNullOrEmpty(): Boolean

Returns true if this nullable map is either null or empty.

Since Kotlin 1.3
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inline operator fun <K, V> Map<out K, V>.iterator(): Iterator<Map.Entry<K, V>>

Returns an Iterator over the entries in the Map.

Since Kotlin 1.0
@JvmName(name = "mutableIterator")
inline operator fun <K, V> MutableMap<K, V>.iterator(): MutableIterator<MutableMap.MutableEntry<K, V>>

Returns a MutableIterator over the mutable entries in the MutableMap.

Since Kotlin 1.0
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inline fun <K, V, R> Map<out K, V>.map(transform: (Map.Entry<K, V>) -> R): List<R>

Returns a list containing the results of applying the given transform function to each entry in the original map.

Since Kotlin 1.0
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inline fun <K, V, R> Map<out K, V>.mapKeys(transform: (Map.Entry<K, V>) -> R): Map<R, V>

Returns a new Map with entries having the keys obtained by applying the transform function to each entry in this Map and the values of this map.

Since Kotlin 1.0
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inline fun <K, V, R, M : MutableMap<in R, in V>> Map<out K, V>.mapKeysTo(destination: M, transform: (Map.Entry<K, V>) -> R): M

Populates the given destination map with entries having the keys obtained by applying the transform function to each entry in this Map and the values of this map.

Since Kotlin 1.0
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inline fun <K, V, R : Any> Map<out K, V>.mapNotNull(transform: (Map.Entry<K, V>) -> R?): List<R>

Returns a list containing only the non-null results of applying the given transform function to each entry in the original map.

Since Kotlin 1.0
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inline fun <K, V, R : Any, C : MutableCollection<in R>> Map<out K, V>.mapNotNullTo(destination: C, transform: (Map.Entry<K, V>) -> R?): C

Applies the given transform function to each entry in the original map and appends only the non-null results to the given destination.

Since Kotlin 1.0
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inline fun <K, V, R, C : MutableCollection<in R>> Map<out K, V>.mapTo(destination: C, transform: (Map.Entry<K, V>) -> R): C

Applies the given transform function to each entry of the original map and appends the results to the given destination.

Since Kotlin 1.0
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inline fun <K, V, R> Map<out K, V>.mapValues(transform: (Map.Entry<K, V>) -> R): Map<K, R>

Returns a new map with entries having the keys of this map and the values obtained by applying the transform function to each entry in this Map.

Since Kotlin 1.0
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inline fun <K, V, R, M : MutableMap<in K, in R>> Map<out K, V>.mapValuesTo(destination: M, transform: (Map.Entry<K, V>) -> R): M

Populates the given destination map with entries having the keys of this map and the values obtained by applying the transform function to each entry in this Map.

Since Kotlin 1.0
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@JvmName(name = "maxByOrThrow")
inline fun <K, V, R : Comparable<R>> Map<out K, V>.maxBy(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>

Returns the first entry yielding the largest value of the given function.

Since Kotlin 1.7
inline fun <K, V, R : Comparable<R>> Map<out K, V>.maxBy(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>?
Since Kotlin 1.0
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.maxByOrNull(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>?

Returns the first entry yielding the largest value of the given function or null if there are no entries.

Since Kotlin 1.4
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.maxOf(selector: (Map.Entry<K, V>) -> R): R
inline fun <K, V> Map<out K, V>.maxOf(selector: (Map.Entry<K, V>) -> Double): Double
inline fun <K, V> Map<out K, V>.maxOf(selector: (Map.Entry<K, V>) -> Float): Float

Returns the largest value among all values produced by selector function applied to each entry in the map.

Since Kotlin 1.4
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.maxOfOrNull(selector: (Map.Entry<K, V>) -> R): R?
inline fun <K, V> Map<out K, V>.maxOfOrNull(selector: (Map.Entry<K, V>) -> Double): Double?
inline fun <K, V> Map<out K, V>.maxOfOrNull(selector: (Map.Entry<K, V>) -> Float): Float?

Returns the largest value among all values produced by selector function applied to each entry in the map or null if there are no entries.

Since Kotlin 1.4
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inline fun <K, V, R> Map<out K, V>.maxOfWith(comparator: Comparator<in R>, selector: (Map.Entry<K, V>) -> R): R

Returns the largest value according to the provided comparator among all values produced by selector function applied to each entry in the map.

Since Kotlin 1.4
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inline fun <K, V, R> Map<out K, V>.maxOfWithOrNull(comparator: Comparator<in R>, selector: (Map.Entry<K, V>) -> R): R?

Returns the largest value according to the provided comparator among all values produced by selector function applied to each entry in the map or null if there are no entries.

Since Kotlin 1.4
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@JvmName(name = "maxWithOrThrow")
inline fun <K, V> Map<out K, V>.maxWith(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>

Returns the first entry having the largest value according to the provided comparator.

Since Kotlin 1.7
inline fun <K, V> Map<out K, V>.maxWith(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>?
Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.maxWithOrNull(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>?

Returns the first entry having the largest value according to the provided comparator or null if there are no entries.

Since Kotlin 1.4
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@JvmName(name = "minByOrThrow")
inline fun <K, V, R : Comparable<R>> Map<out K, V>.minBy(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>

Returns the first entry yielding the smallest value of the given function.

Since Kotlin 1.7
inline fun <K, V, R : Comparable<R>> Map<out K, V>.minBy(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>?
Since Kotlin 1.0
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.minByOrNull(selector: (Map.Entry<K, V>) -> R): Map.Entry<K, V>?

Returns the first entry yielding the smallest value of the given function or null if there are no entries.

Since Kotlin 1.4
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.minOf(selector: (Map.Entry<K, V>) -> R): R
inline fun <K, V> Map<out K, V>.minOf(selector: (Map.Entry<K, V>) -> Double): Double
inline fun <K, V> Map<out K, V>.minOf(selector: (Map.Entry<K, V>) -> Float): Float

Returns the smallest value among all values produced by selector function applied to each entry in the map.

Since Kotlin 1.4
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inline fun <K, V, R : Comparable<R>> Map<out K, V>.minOfOrNull(selector: (Map.Entry<K, V>) -> R): R?
inline fun <K, V> Map<out K, V>.minOfOrNull(selector: (Map.Entry<K, V>) -> Double): Double?
inline fun <K, V> Map<out K, V>.minOfOrNull(selector: (Map.Entry<K, V>) -> Float): Float?

Returns the smallest value among all values produced by selector function applied to each entry in the map or null if there are no entries.

Since Kotlin 1.4
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inline fun <K, V, R> Map<out K, V>.minOfWith(comparator: Comparator<in R>, selector: (Map.Entry<K, V>) -> R): R

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each entry in the map.

Since Kotlin 1.4
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inline fun <K, V, R> Map<out K, V>.minOfWithOrNull(comparator: Comparator<in R>, selector: (Map.Entry<K, V>) -> R): R?

Returns the smallest value according to the provided comparator among all values produced by selector function applied to each entry in the map or null if there are no entries.

Since Kotlin 1.4
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operator fun <K, V> Map<out K, V>.minus(key: K): Map<K, V>

Returns a map containing all entries of the original map except the entry with the given key.

Since Kotlin 1.1
operator fun <K, V> Map<out K, V>.minus(keys: Array<out K>): Map<K, V>

Returns a map containing all entries of the original map except those entries the keys of which are contained in the given keys array.

Since Kotlin 1.1
operator fun <K, V> Map<out K, V>.minus(keys: Iterable<K>): Map<K, V>

Returns a map containing all entries of the original map except those entries the keys of which are contained in the given keys collection.

Since Kotlin 1.1
operator fun <K, V> Map<out K, V>.minus(keys: Sequence<K>): Map<K, V>

Returns a map containing all entries of the original map except those entries the keys of which are contained in the given keys sequence.

Since Kotlin 1.1
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inline operator fun <K, V> MutableMap<K, V>.minusAssign(key: K)

Removes the entry with the given key from this mutable map.

Since Kotlin 1.1
inline operator fun <K, V> MutableMap<K, V>.minusAssign(keys: Array<out K>)

Removes all entries the keys of which are contained in the given keys array from this mutable map.

Since Kotlin 1.1
inline operator fun <K, V> MutableMap<K, V>.minusAssign(keys: Iterable<K>)

Removes all entries the keys of which are contained in the given keys collection from this mutable map.

Since Kotlin 1.1
inline operator fun <K, V> MutableMap<K, V>.minusAssign(keys: Sequence<K>)

Removes all entries from the keys of which are contained in the given keys sequence from this mutable map.

Since Kotlin 1.1
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@JvmName(name = "minWithOrThrow")
inline fun <K, V> Map<out K, V>.minWith(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>

Returns the first entry having the smallest value according to the provided comparator.

Since Kotlin 1.7
fun <K, V> Map<out K, V>.minWith(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>?
Since Kotlin 1.0
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inline fun <K, V> Map<out K, V>.minWithOrNull(comparator: Comparator<in Map.Entry<K, V>>): Map.Entry<K, V>?

Returns the first entry having the smallest value according to the provided comparator or null if there are no entries.

Since Kotlin 1.4
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fun <K, V> Map<out K, V>.none(): Boolean

Returns true if the map has no entries.

Since Kotlin 1.0
inline fun <K, V> Map<out K, V>.none(predicate: (Map.Entry<K, V>) -> Boolean): Boolean

Returns true if no entries match the given predicate.

Since Kotlin 1.0
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inline fun <K, V> Map<K, V>?.orEmpty(): Map<K, V>

Returns the Map if its not null, or the empty Map otherwise.

Since Kotlin 1.0
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operator fun <K, V> Map<out K, V>.plus(pairs: Array<out Pair<K, V>>): Map<K, V>

Creates a new read-only map by replacing or adding entries to this map from a given array of key-value pairs.

Since Kotlin 1.0
operator fun <K, V> Map<out K, V>.plus(pair: Pair<K, V>): Map<K, V>

Creates a new read-only map by replacing or adding an entry to this map from a given key-value pair.

Since Kotlin 1.0
operator fun <K, V> Map<out K, V>.plus(pairs: Iterable<Pair<K, V>>): Map<K, V>

Creates a new read-only map by replacing or adding entries to this map from a given collection of key-value pairs.

Since Kotlin 1.0
operator fun <K, V> Map<out K, V>.plus(map: Map<out K, V>): Map<K, V>

Creates a new read-only map by replacing or adding entries to this map from another map.

Since Kotlin 1.0
operator fun <K, V> Map<out K, V>.plus(pairs: Sequence<Pair<K, V>>): Map<K, V>

Creates a new read-only map by replacing or adding entries to this map from a given sequence of key-value pairs.

Since Kotlin 1.0
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inline operator fun <K, V> MutableMap<in K, in V>.plusAssign(pairs: Array<out Pair<K, V>>)

Appends or replaces all pairs from the given array of pairs in this mutable map.

Since Kotlin 1.0
inline operator fun <K, V> MutableMap<in K, in V>.plusAssign(pair: Pair<K, V>)

Appends or replaces the given pair in this mutable map.

Since Kotlin 1.0
inline operator fun <K, V> MutableMap<in K, in V>.plusAssign(pairs: Iterable<Pair<K, V>>)

Appends or replaces all pairs from the given collection of pairs in this mutable map.

Since Kotlin 1.0
inline operator fun <K, V> MutableMap<in K, in V>.plusAssign(map: Map<K, V>)

Appends or replaces all entries from the given map in this mutable map.

Since Kotlin 1.0
inline operator fun <K, V> MutableMap<in K, in V>.plusAssign(pairs: Sequence<Pair<K, V>>)

Appends or replaces all pairs from the given sequence of pairs in this mutable map.

Since Kotlin 1.0
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expect abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.0
actual abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.1
actual abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.0
actual abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.3
actual abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.8
actual abstract fun put(key: K, value: V): V?

Associates the specified value with the specified key in the map.

Since Kotlin 1.8
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expect abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.0
actual abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.1
actual abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.0
actual abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.3
actual abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.8
actual abstract fun putAll(from: Map<out K, V>)

Updates this map with key/value pairs from the specified map from.

Since Kotlin 1.8
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fun <K, V> MutableMap<in K, in V>.putAll(pairs: Array<out Pair<K, V>>)

Puts all the given pairs into this MutableMap with the first component in the pair being the key and the second the value.

Since Kotlin 1.0
fun <K, V> MutableMap<in K, in V>.putAll(pairs: Iterable<Pair<K, V>>)

Puts all the elements of the given collection into this MutableMap with the first component in the pair being the key and the second the value.

Since Kotlin 1.0
fun <K, V> MutableMap<in K, in V>.putAll(pairs: Sequence<Pair<K, V>>)

Puts all the elements of the given sequence into this MutableMap with the first component in the pair being the key and the second the value.

Since Kotlin 1.0
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expect abstract fun remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.0
actual abstract fun remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.1
actual abstract fun remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.3
actual abstract fun remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.8
actual abstract fun remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.8
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inline fun <K, V> MutableMap<out K, V>.remove(key: K): V?

Removes the specified key and its corresponding value from this map.

Since Kotlin 1.0
inline fun <K, V> MutableMap<out K, out V>.remove(key: K, value: V): Boolean

Removes the entry for the specified key only if it is currently mapped to the specified value.

Since Kotlin 1.2
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inline operator fun <K, V> MutableMap<K, V>.set(key: K, value: V)

Allows to use the index operator for storing values in a mutable map.

Since Kotlin 1.0
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inline operator fun <V> MutableMap<in String, in V>.setValue(thisRef: Any?, property: KProperty<*>, value: V)

Stores the value of the property for the given object in this mutable map.

Since Kotlin 1.0
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fun <K, V> Map<out K, V>.toList(): List<Pair<K, V>>

Returns a List containing all key-value pairs.

Since Kotlin 1.0
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fun <K, V> Map<out K, V>.toMap(): Map<K, V>

Returns a new read-only map containing all key-value pairs from the original map.

Since Kotlin 1.1
fun <K, V, M : MutableMap<in K, in V>> Map<out K, V>.toMap(destination: M): M

Populates and returns the destination mutable map with key-value pairs from the given map.

Since Kotlin 1.1
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fun <K, V> Map<out K, V>.toMutableMap(): MutableMap<K, V>

Returns a new mutable map containing all key-value pairs from the original map.

Since Kotlin 1.1
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inline fun Map<String, String>.toProperties(): Properties

Converts this Map to a Properties object.

Since Kotlin 1.0
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fun <K : Comparable<K>, V> Map<out K, V>.toSortedMap(): SortedMap<K, V>

Converts this Map to a SortedMap. The resulting SortedMap determines the equality and order of keys according to their natural sorting order.

Since Kotlin 1.0
fun <K, V> Map<out K, V>.toSortedMap(comparator: Comparator<in K>): SortedMap<K, V>

Converts this Map to a SortedMap. The resulting SortedMap determines the equality and order of keys according to the sorting order provided by the given comparator.

Since Kotlin 1.0
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fun <K, V> Map<K, V>.withDefault(defaultValue: (key: K) -> V): Map<K, V>

Returns a wrapper of this read-only map, having the implicit default value provided with the specified function defaultValue.

Since Kotlin 1.0
@JvmName(name = "withDefaultMutable")
fun <K, V> MutableMap<K, V>.withDefault(defaultValue: (key: K) -> V): MutableMap<K, V>

Returns a wrapper of this mutable map, having the implicit default value provided with the specified function defaultValue.

Since Kotlin 1.0