Module java.base
Package java.util.concurrent

Class ConcurrentHashMap.KeySetView<K,V>

java.lang.Object
java.util.concurrent.ConcurrentHashMap.KeySetView<K,V>
All Implemented Interfaces:
Serializable, Iterable<K>, Collection<K>, Set<K>
Enclosing class:
ConcurrentHashMap<K,V>
public static class ConcurrentHashMap.KeySetView<K,V> extends Object implements Set<K>, Serializable
A view of a ConcurrentHashMap as a Set of keys, in which additions may optionally be enabled by mapping to a common value. This class cannot be directly instantiated. See keySet(), keySet(V), newKeySet(), newKeySet(int).
Since:
1.8
See Also:

  • Method Details

    • getMappedValue

      public V getMappedValue()
      Returns the default mapped value for additions, or null if additions are not supported.
      Returns:
      the default mapped value for additions, or null if not supported

    • contains

      public boolean contains(Object o)
      Specified by:
      contains in interface Collection<K>
      Specified by:
      contains in interface Set<K>
      Throws:
      NullPointerException - if the specified key is null

    • remove

      public boolean remove(Object o)
      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.
      Specified by:
      remove in interface Collection<K>
      Specified by:
      remove in interface Set<K>
      Parameters:
      o - the key to be removed from the backing map
      Returns:
      true if the backing map contained the specified key
      Throws:
      NullPointerException - if the specified key is null

    • iterator

      public Iterator<K> iterator()
      Returns an iterator over the elements in this collection.

      The returned iterator is weakly consistent.

      Specified by:
      iterator in interface Collection<K>
      Specified by:
      iterator in interface Iterable<K>
      Specified by:
      iterator in interface Set<K>
      Returns:
      an iterator over the keys of the backing map

    • add

      public boolean add(K e)
      Adds the specified key to this set view by mapping the key to the default mapped value in the backing map, if defined.
      Specified by:
      add in interface Collection<K>
      Specified by:
      add in interface Set<K>
      Parameters:
      e - key to be added
      Returns:
      true if this set changed as a result of the call
      Throws:
      NullPointerException - if the specified key is null
      UnsupportedOperationException - if no default mapped value for additions was provided

    • addAll

      public boolean addAll(Collection<? extends K> c)
      Adds all of the elements in the specified collection to this set, as if by calling add(K) on each one.
      Specified by:
      addAll in interface Collection<K>
      Specified by:
      addAll in interface Set<K>
      Parameters:
      c - the elements to be inserted into this set
      Returns:
      true if this set changed as a result of the call
      Throws:
      NullPointerException - if the collection or any of its elements are null
      UnsupportedOperationException - if no default mapped value for additions was provided

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface Collection<K>
      Specified by:
      hashCode in interface Set<K>
      Overrides:
      hashCode in class Object

    • equals

      public boolean equals(Object o)
      Specified by:
      equals in interface Collection<K>
      Specified by:
      equals in interface Set<K>
      Overrides:
      equals in class Object

    • getMap

      public ConcurrentHashMap<K,V> getMap()
      Returns the map backing this view.
      Returns:
      the map backing this view

    • clear

      public final void clear()
      Removes all of the elements from this view, by removing all the mappings from the map backing this view.
      Specified by:
      clear in interface Collection<K>

    • size

      public final int size()
      Specified by:
      size in interface Collection<K>

    • isEmpty

      public final boolean isEmpty()
      Specified by:
      isEmpty in interface Collection<K>

    • toArray

      public final Object[] toArray()
      Specified by:
      toArray in interface Collection<K>

    • toArray

      public final <T> T[] toArray(T[] a)
      Specified by:
      toArray in interface Collection<K>

    • toString

      public final String toString()
      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).
      Overrides:
      toString in class Object
      Returns:
      a string representation of this collection

    • containsAll

      public final boolean containsAll(Collection<?> c)
      Specified by:
      containsAll in interface Collection<K>

    • removeAll

      public boolean removeAll(Collection<?> c)
      Specified by:
      removeAll in interface Collection<K>

    • retainAll

      public final boolean retainAll(Collection<?> c)
      Specified by:
      retainAll in interface Collection<K>