Thread-safe HashSet with Guava Collections

问题:

Like the title says, i would like to get a thread-safe HashSet using Guava Collections.

Can you help me?

Thanks!

回答1:

Set<K> set = Collections.newSetFromMap(new ConcurrentHashMap<K, Boolean>());

回答2:

This would be the right answer, Using the Sets class from Guava. Anyway the answer from @crhis was good intended.

Sets.newSetFromMap(new ConcurrentHashMap<V, Boolean>());

回答3:

Google Collections had a factory method named Sets.newConcurrentHashSet() for a while.

Its implementation was similar to Chris's suggestion:

public static <E> Set<E> newConcurrentHashSet() {
  return newSetFromMap(new ConcurrentHashMap<E, Boolean>());
}

They had a newSetFromMap() method inside the com.google.common.collect.Sets class (written by Doug Lea with assistance from members of JCP JSR-166). That method was added to java.util.Collections in java 1.6.

It was withdrawn in Google Collections 1.0rc1, since there are plans to better support concurrent sets in Guava (more information here).

This post expands on the use of the "newSetFromMap" method to construct concurrent sets.

回答4:

Java 8 introduces new way to create concurrent hash set - ConcurrentHashMap.newKeySet()

Set<K> set = ConcurrentHashMap.newKeySet();

It's shorter than wrapping in Collections.newSetFromMap