Does .asSet(...) exist in any API?

Question

Now with Java 8 you can do this without need of third-party framework:

Set<String> set = Stream.of("a","b","c").collect(Collectors.toSet());

See Collectors.

Enjoy!

Using Guava, it is as simple as that:

Set<String> mySet = ImmutableSet.<String> of("a", "b");

Or for a mutable set:

Set<String> mySet = Sets.newHashSet("a", "b")

For more data types see the Guava user guide

You could use

new HashSet<String>(Arrays.asList("a","b"));

For the special cases of sets with zero or one members, you can use:

java.util.Collections.EMPTY_SET

and:

java.util.Collections.singleton("A")

In Java 9, similar function has been added via factory methods:

Set<String> oneLinerSet = Set.of("a", "b", ...);

(There are equivalents for List as well.)

As others have said, use:

new HashSet<String>(Arrays.asList("a","b"));

The reason this does not exist in Java is that Arrays.asList returns a fixed sized list, in other words:

public static void main(String a[])
{
  List<String> myList = Arrays.asList("a", "b");
  myList.add("c");
}

Returns:

Exception in thread "main" java.lang.UnsupportedOperationException
    at java.util.AbstractList.add(Unknown Source)
    at java.util.AbstractList.add(Unknown Source)

There is no JDK implementation of a "fixed-size" Set inside the Arrays class. Why do you want this? A Set guarantees that there are no duplicates, but if you are typing them out by hand, you shouldn't need that functionality... and List has more methods. Both interfaces extend Collection and Iterable.

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As others have said, use guava If you really want this functionality - since it's not in the JDK. Look at their answers (in particular Michael Schmeißer's answer) for information on that.