如何将Java 8流收集到Guava ImmutableCollection中？ [英] How can I collect a Java 8 stream into a Guava ImmutableCollection?

问题描述

我想执行以下操作：

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

但是结果列表是Guava的 ImmutableList <的实现方式/ code>。

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

我知道我能做到

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

但我想直接收款。我试过了

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

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

但它引发了一个例外：

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

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

推荐答案

Alexis接受的答案中的 toImmutableList（）方法现在包含在 Guava 21 ，可以用作：

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());

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