ScatterMap
public sealed class ScatterMap<K extends Object, V extends Object>
MutableScatterMap |
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ScatterMap is a container with a Map-like interface based on a flat hash table implementation (the key/value mappings are not stored by nodes but directly into arrays). The underlying implementation is designed to avoid all allocations on insertion, removal, retrieval, and iteration. Allocations may still happen on insertion when the underlying storage needs to grow to accommodate newly added entries to the table. In addition, this implementation minimizes memory usage by avoiding the use of separate objects to hold key/value pairs.
This implementation makes no guarantee as to the order of the keys and values stored, nor does it make guarantees that the order remains constant over time.
This implementation is not thread-safe: if multiple threads access this container concurrently, and one or more threads modify the structure of the map (insertion or removal for instance), the calling code must provide the appropriate synchronization. Multiple threads are safe to read from this map concurrently if no write is happening.
This implementation is read-only and only allows data to be queried. A mutable implementation is provided by MutableScatterMap.
Note: when a Map is absolutely necessary, you can use the method asMap to create a thin wrapper around a ScatterMap. Please refer to asMap for more details and caveats.
ScatterMap and SimpleArrayMap: like SimpleArrayMap, ScatterMap/MutableScatterMap is designed to avoid the allocation of extra objects when inserting new entries in the map. However, the implementation of ScatterMap/MutableScatterMap offers better performance characteristics compared to SimpleArrayMap and is thus generally preferable. If memory usage is a concern, SimpleArrayMap automatically shrinks its storage to avoid using more memory than necessary. You can also control memory usage with MutableScatterMap by manually calling MutableScatterMap.trim.
| See also | |
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MutableScatterMap |
Summary
Protected constructors |
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<K extends Object, V extends Object> ScatterMap() |
Public methods |
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final boolean |
Returns true if all entries match the given |
final boolean |
any()Returns |
final boolean |
Returns true if at least one entry matches the given |
final @NonNull Map<@NonNull K, @NonNull V> |
asMap()Wraps this |
final boolean |
Returns true if the specified |
final boolean |
containsKey(@NonNull K key)Returns true if the specified |
final boolean |
containsValue(@NonNull V value)Returns true if the specified |
final int |
count()Returns the number of entries in this map. |
final int |
Returns the number of entries matching the given |
boolean |
Compares the specified object |
final void |
Iterates over every key/value pair stored in this map by invoking the specified |
final void |
forEachKey(@NonNull Function1<@NonNull key, Unit> block)Iterates over every key stored in this map by invoking the specified |
final void |
forEachValue(@NonNull Function1<@NonNull value, Unit> block)Iterates over every value stored in this map by invoking the specified |
final V |
Returns the value corresponding to the given |
final int |
Returns the number of key-value pairs that can be stored in this map without requiring internal storage reallocation. |
final @NonNull V |
getOrDefault(@NonNull K key, @NonNull V defaultValue)Returns the value to which the specified |
final @NonNull V |
Returns the value for the given |
final int |
getSize()Returns the number of key-value pairs in this map. |
int |
hashCode()Returns the hash code value for this map. |
final boolean |
isEmpty()Indicates whether this map is empty. |
final boolean |
Returns |
final @NonNull String |
joinToString(Creates a String from the elements separated by |
final boolean |
none()Returns |
@NonNull String |
toString()Returns a string representation of this map. |
Protected constructors
Public methods
all
public final boolean all(@NonNull Function2<@NonNull K, @NonNull V, @NonNull Boolean> predicate)
Returns true if all entries match the given predicate.
any
public final boolean any(@NonNull Function2<@NonNull K, @NonNull V, @NonNull Boolean> predicate)
Returns true if at least one entry matches the given predicate.
asMap
public final @NonNull Map<@NonNull K, @NonNull V> asMap()
Wraps this ScatterMap with a Map interface. The Map is backed by the ScatterMap, so changes to the ScatterMap are reflected in the Map. If the ScatterMap is modified while an iteration over the Map is in progress, the results of the iteration are undefined.
Note: while this method is useful to use this ScatterMap with APIs accepting Map interfaces, it is less efficient to do so than to use ScatterMap's APIs directly. While the Map implementation returned by this method tries to be as efficient as possible, the semantics of Map may require the allocation of temporary objects for access and iteration.
contains
public final boolean contains(@NonNull K key)
Returns true if the specified key is present in this hash map, false otherwise.
containsKey
public final boolean containsKey(@NonNull K key)
Returns true if the specified key is present in this hash map, false otherwise.
containsValue
public final boolean containsValue(@NonNull V value)
Returns true if the specified value is present in this hash map, false otherwise.
count
public final int count(@NonNull Function2<@NonNull K, @NonNull V, @NonNull Boolean> predicate)
Returns the number of entries matching the given predicate.
equals
public boolean equals(Object other)
Compares the specified object other with this hash map for equality. The two objects are considered equal if other:
-
Is a
ScatterMap -
Has the same
sizeas this map -
Contains key/value pairs equal to this map's pair
forEach
public final void forEach(@NonNull Function2<@NonNull key, @NonNull value, Unit> block)
Iterates over every key/value pair stored in this map by invoking the specified block lambda.
forEachKey
public final void forEachKey(@NonNull Function1<@NonNull key, Unit> block)
Iterates over every key stored in this map by invoking the specified block lambda.
forEachValue
public final void forEachValue(@NonNull Function1<@NonNull value, Unit> block)
Iterates over every value stored in this map by invoking the specified block lambda.
get
public final V get(@NonNull K key)
Returns the value corresponding to the given key, or null if such a key is not present in the map.
getCapacity
public final int getCapacity()
Returns the number of key-value pairs that can be stored in this map without requiring internal storage reallocation.
getOrDefault
public final @NonNull V getOrDefault(@NonNull K key, @NonNull V defaultValue)
Returns the value to which the specified key is mapped, or defaultValue if this map contains no mapping for the key.
getOrElse
public final @NonNull V getOrElse(@NonNull K key, @NonNull Function0<@NonNull V> defaultValue)
Returns the value for the given key if the value is present and not null. Otherwise, returns the result of the defaultValue function.
getSize
public final int getSize()
Returns the number of key-value pairs in this map.
hashCode
public int hashCode()
Returns the hash code value for this map. The hash code the sum of the hash codes of each key/value pair.
joinToString
public final @NonNull String joinToString(
@NonNull CharSequence separator,
@NonNull CharSequence prefix,
@NonNull CharSequence postfix,
int limit,
@NonNull CharSequence truncated,
Function2<@NonNull key, @NonNull value, @NonNull CharSequence> transform
)
Creates a String from the elements separated by separator and using prefix before and postfix after, if supplied.
When a non-negative value of limit is provided, a maximum of limit items are used to generate the string. If the collection holds more than limit items, the string is terminated with truncated.
transform may be supplied to convert each element to a custom String.