Class ConcurrentHashSet<E>

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.Set<E>

    public class ConcurrentHashSet<E>
    extends java.util.AbstractSet<E>
    implements java.io.Serializable
    A simple Set implementation backed by a ConcurrentHashMap to deal with the fact that the JDK does not have a proper concurrent Set implementation that uses efficient lock striping.

    Note that values are stored as keys in the underlying Map, with a static dummy object as value.

    Since:
    4.0
    Author:
    Manik Surtani
    See Also:
    Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected java.util.concurrent.ConcurrentMap<E,​java.lang.Object> map  
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean add​(E o)  
      boolean addAll​(java.util.Collection<? extends E> c)  
      void clear()  
      boolean contains​(java.lang.Object o)  
      boolean containsAll​(java.util.Collection<?> c)  
      boolean isEmpty()  
      java.util.Iterator<E> iterator()  
      boolean remove​(java.lang.Object o)  
      boolean removeAll​(java.util.Collection<?> c)  
      boolean retainAll​(java.util.Collection<?> c)  
      int size()  
      java.lang.Object[] toArray()  
      <T> T[] toArray​(T[] a)  
      • Methods inherited from class java.util.AbstractSet

        equals, hashCode
      • Methods inherited from class java.util.AbstractCollection

        toString
      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait
      • Methods inherited from interface java.util.Collection

        parallelStream, removeIf, stream, toArray
      • Methods inherited from interface java.lang.Iterable

        forEach
      • Methods inherited from interface java.util.Set

        spliterator
    • Field Detail

      • map

        protected final java.util.concurrent.ConcurrentMap<E,​java.lang.Object> map
    • Constructor Detail

      • ConcurrentHashSet

        public ConcurrentHashSet()
      • ConcurrentHashSet

        public ConcurrentHashSet​(int concurrencyLevel)
        Parameters:
        concurrencyLevel - passed in to the underlying CHM. See ConcurrentHashMap(int, float, int) javadocs for details.
      • ConcurrentHashSet

        public ConcurrentHashSet​(int initSize,
                                 float loadFactor,
                                 int concurrencyLevel)
        Params passed in to the underlying CHM. See ConcurrentHashMap(int, float, int) javadocs for details.
    • Method Detail

      • size

        public int size()
        Specified by:
        size in interface java.util.Collection<E>
        Specified by:
        size in interface java.util.Set<E>
        Specified by:
        size in class java.util.AbstractCollection<E>
      • isEmpty

        public boolean isEmpty()
        Specified by:
        isEmpty in interface java.util.Collection<E>
        Specified by:
        isEmpty in interface java.util.Set<E>
        Overrides:
        isEmpty in class java.util.AbstractCollection<E>
      • contains

        public boolean contains​(java.lang.Object o)
        Specified by:
        contains in interface java.util.Collection<E>
        Specified by:
        contains in interface java.util.Set<E>
        Overrides:
        contains in class java.util.AbstractCollection<E>
      • iterator

        public java.util.Iterator<E> iterator()
        Specified by:
        iterator in interface java.util.Collection<E>
        Specified by:
        iterator in interface java.lang.Iterable<E>
        Specified by:
        iterator in interface java.util.Set<E>
        Specified by:
        iterator in class java.util.AbstractCollection<E>
      • toArray

        public java.lang.Object[] toArray()
        Specified by:
        toArray in interface java.util.Collection<E>
        Specified by:
        toArray in interface java.util.Set<E>
        Overrides:
        toArray in class java.util.AbstractCollection<E>
      • toArray

        public <T> T[] toArray​(T[] a)
        Specified by:
        toArray in interface java.util.Collection<E>
        Specified by:
        toArray in interface java.util.Set<E>
        Overrides:
        toArray in class java.util.AbstractCollection<E>
      • add

        public boolean add​(E o)
        Specified by:
        add in interface java.util.Collection<E>
        Specified by:
        add in interface java.util.Set<E>
        Overrides:
        add in class java.util.AbstractCollection<E>
      • remove

        public boolean remove​(java.lang.Object o)
        Specified by:
        remove in interface java.util.Collection<E>
        Specified by:
        remove in interface java.util.Set<E>
        Overrides:
        remove in class java.util.AbstractCollection<E>
      • containsAll

        public boolean containsAll​(java.util.Collection<?> c)
        Specified by:
        containsAll in interface java.util.Collection<E>
        Specified by:
        containsAll in interface java.util.Set<E>
        Overrides:
        containsAll in class java.util.AbstractCollection<E>
      • addAll

        public boolean addAll​(java.util.Collection<? extends E> c)
        Specified by:
        addAll in interface java.util.Collection<E>
        Specified by:
        addAll in interface java.util.Set<E>
        Overrides:
        addAll in class java.util.AbstractCollection<E>
      • retainAll

        public boolean retainAll​(java.util.Collection<?> c)
        Specified by:
        retainAll in interface java.util.Collection<E>
        Specified by:
        retainAll in interface java.util.Set<E>
        Overrides:
        retainAll in class java.util.AbstractCollection<E>
      • removeAll

        public boolean removeAll​(java.util.Collection<?> c)
        Specified by:
        removeAll in interface java.util.Collection<E>
        Specified by:
        removeAll in interface java.util.Set<E>
        Overrides:
        removeAll in class java.util.AbstractSet<E>
      • clear

        public void clear()
        Specified by:
        clear in interface java.util.Collection<E>
        Specified by:
        clear in interface java.util.Set<E>
        Overrides:
        clear in class java.util.AbstractCollection<E>