Hashtable

Hashtable

Hashtable()

Constructs a new, empty hashtable with a default initial capacity (11) and load factor (0.75).

Hashtable

Hashtable(initialCapacity: Int)

Constructs a new, empty hashtable with the specified initial capacity and default load factor (0.75).

Hashtable

Hashtable(
    initialCapacity: Int, 
    loadFactor: Float)

Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.

Hashtable

Hashtable(t: MutableMap<out K, out V>!)

Constructs a new hashtable with the same mappings as the given Map. The hashtable is created with an initial capacity sufficient to hold the mappings in the given Map and a default load factor (0.75).

clear

open fun clear(): Unit

Clears this hashtable so that it contains no keys.

clone

open fun clone(): Any

Creates a shallow copy of this hashtable. All the structure of the hashtable itself is copied, but the keys and values are not cloned. This is a relatively expensive operation.

compute

open fun compute(
    key: K, 
    remappingFunction: BiFunction<in K, in V?, out V?>
): V?

Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). For example, to either create or append a String msg to a value mapping:

<code>map.compute(key, (k, v) -&gt; (v == null) ? msg : v.concat(msg))</code>

If the remapping function returns null, the mapping is removed (or remains absent if initially absent). If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

The remapping function should not modify this map during computation.

This method will, on a best-effort basis, throw a java.util.ConcurrentModificationException if the remapping function modified this map during computation.

computeIfAbsent

open fun computeIfAbsent(
    key: K, 
    mappingFunction: Function<in K, out V>
): V

If the specified key is not already associated with a value (or is mapped to null), attempts to compute its value using the given mapping function and enters it into this map unless null.

If the mapping function returns null, no mapping is recorded. If the mapping function itself throws an (unchecked) exception, the exception is rethrown, and no mapping is recorded. The most common usage is to construct a new object serving as an initial mapped value or memoized result, as in:

<code>map.computeIfAbsent(key, k -&gt; new Value(f(k)));
  </code>

Or to implement a multi-value map, Map<K,Collection<V>>, supporting multiple values per key:

<code>map.computeIfAbsent(key, k -&gt; new HashSet&lt;V&gt;()).add(v);
  </code>

The mapping function should not modify this map during computation.

This method will, on a best-effort basis, throw a java.util.ConcurrentModificationException if the mapping function modified this map during computation.

computeIfPresent

open fun computeIfPresent(
    key: K, 
    remappingFunction: BiFunction<in K, in V, out V?>
): V?

If the value for the specified key is present and non-null, attempts to compute a new mapping given the key and its current mapped value.

If the remapping function returns null, the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

The remapping function should not modify this map during computation.

This method will, on a best-effort basis, throw a java.util.ConcurrentModificationException if the remapping function modified this map during computation.

contains

open fun contains(value: Any!): Boolean

Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.

Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the collections framework).

containsKey

open fun containsKey(key: K): Boolean

Tests if the specified object is a key in this hashtable.

containsValue

open fun containsValue(value: V): Boolean

Returns true if this hashtable maps one or more keys to this value.

Note that this method is identical in functionality to contains (which predates the Map interface).

elements

open fun elements(): Enumeration<V>!

Returns an enumeration of the values in this hashtable. Use the Enumeration methods on the returned object to fetch the elements sequentially. If the hashtable is structurally modified while enumerating over the values then the results of enumerating are undefined.

equals

open fun equals(other: Any?): Boolean

Compares the specified Object with this Map for equality, as per the definition in the Map interface.

forEach

open fun forEach(action: BiConsumer<in K, in V>): Unit

get

open fun get(key: K): V?

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

More formally, if this map contains a mapping from a key k to a value v such that (key.equals(k)), then this method returns v; otherwise it returns null. (There can be at most one such mapping.)

getOrDefault

open fun getOrDefault(
    key: K, 
    defaultValue: V
): V

hashCode

open fun hashCode(): Int

Returns the hash code value for this Map as per the definition in the Map interface.

isEmpty

open fun isEmpty(): Boolean

Tests if this hashtable maps no keys to values.

keys

open fun keys(): Enumeration<K>!

Returns an enumeration of the keys in this hashtable. Use the Enumeration methods on the returned object to fetch the keys sequentially. If the hashtable is structurally modified while enumerating over the keys then the results of enumerating are undefined.

merge

open fun merge(
    key: K, 
    value: V, 
    remappingFunction: BiFunction<in V, in V, out V?>
): V?

If the specified key is not already associated with a value or is associated with null, associates it with the given non-null value. Otherwise, replaces the associated value with the results of the given remapping function, or removes if the result is null. This method may be of use when combining multiple mapped values for a key. For example, to either create or append a String msg to a value mapping:

<code>map.merge(key, msg, String::concat)
  </code>

If the remapping function returns null, the mapping is removed. If the remapping function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged.

The remapping function should not modify this map during computation.

This method will, on a best-effort basis, throw a java.util.ConcurrentModificationException if the remapping function modified this map during computation.

put

open fun put(
    key: K, 
    value: V
): V?

Maps the specified key to the specified value in this hashtable. Neither the key nor the value can be null.

The value can be retrieved by calling the get method with a key that is equal to the original key.

putAll

open fun putAll(from: Map<out K, V>): Unit

Copies all of the mappings from the specified map to this hashtable. These mappings will replace any mappings that this hashtable had for any of the keys currently in the specified map.

putIfAbsent

open fun putIfAbsent(
    key: K, 
    value: V
): V?

remove

open fun remove(key: K): V?

Removes the key (and its corresponding value) from this hashtable. This method does nothing if the key is not in the hashtable.

remove

open fun remove(
    key: K, 
    value: V
): Boolean

replace

open fun replace(
    key: K, 
    value: V
): V?

replace

open fun replace(
    key: K, 
    oldValue: V, 
    newValue: V
): Boolean

replaceAll

open fun replaceAll(function: BiFunction<in K, in V, out V>): Unit

toString

open fun toString(): String

Returns a string representation of this Hashtable object in the form of a set of entries, enclosed in braces and separated by the ASCII characters " , " (comma and space). Each entry is rendered as the key, an equals sign =, and the associated element, where the toString method is used to convert the key and element to strings.

rehash

protected open fun rehash(): Unit

Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.

entries

open val entries: MutableSet<MutableEntry<K, V>>

Returns a Set view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation, or through the setValue operation on a map entry returned by the iterator) the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.

keys

open val keys: MutableSet<K>

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

size

open val size: Int

Returns the number of keys in this hashtable.

values

open val values: MutableCollection<V>

Returns a Collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.