How can I collect a Java 8 stream into a Guava ImmutableCollection?

Question

I would like to do the following:

List<Integer> list = IntStream.range(0, 7).collect(Collectors.toList()); 

but in a way that the resulting list is an implementation of Guava's ImmutableList.

I know I could do

List<Integer> list = IntStream.range(0, 7).collect(Collectors.toList()); List<Integer> immutableList = ImmutableList.copyOf(list); 

but I would like to collect to it directly. I've tried

List<Integer> list = IntStream.range(0, 7)     .collect(Collectors.toCollection(ImmutableList::of)); 

but it threw an exception:

java.lang.UnsupportedOperationException at com.google.common.collect.ImmutableCollection.add(ImmutableCollection.java:96)

Answer 1

The toImmutableList() method in the accepted answer of Alexis is now included in Guava 21 and can be used as:

ImmutableList<Integer> list = IntStream.range(0, 7)     .boxed()     .collect(ImmutableList.toImmutableList()); 

Edit: Removed @Beta from ImmutableList.toImmutableList along with other frequently used APIs in Release 27.1 (6242bdd).