如何将 Java 8 流收集到 Guava ImmutableCollection 中?

问题描述

我想做以下事情:

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

但在某种程度上，结果列表是 Guava 的 ImmutableList 的实现.

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);

但我想直接收集到它.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));

但它引发了异常:

java.lang.UnsupportedOperationException在 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 并可用作:

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());

从 ImmutableList.toImmutableList 中删除 @Beta 以及 发布 27.1 (6242bdd).

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

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