将 Java 数组转换为可迭代的 [英] Convert Java Array to Iterable

问题描述

我有一个原始数组，例如 int、int[] foo.它可能是小型的，也可能不是.

I have an Array of primitives, for example for int, int[] foo. It might be a small sized one, or not.

int foo[] = {1,2,3,4,5,6,7,8,9,0};

从中创建 Iterable 的最佳方法是什么?

What is the best way to create an Iterable<Integer> from it?

Iterable<Integer> fooBar = convert(foo);

注意事项:

请不要使用循环来回答(除非你能很好地解释编译器如何对它们做一些聪明的事情?)

Please do not answer using loops (unless you can give a good explanation on how the compiler do something smart about them?)

还要注意

int a[] = {1,2,3};
List<Integer> l = Arrays.asList(a);

甚至不会编译

Type mismatch: cannot convert from List<int[]> to List<Integer>

还要检查为什么数组不能分配给 Iterable?在回答之前.

此外，如果您使用某个库(例如 Guava)，请解释为什么这是最好的.(因为它来自谷歌不是一个完整的答案:P)

Also, if you use some library (e.g., Guava), please explain why this is the Best. ( Because its from Google is not a complete answer :P )

最后，因为似乎有一个家庭作业，避免发布家庭作业代码.

Last, since there seems to be a homework about that, avoid posting homeworkish code.

推荐答案

Integer foo[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

List<Integer> list = Arrays.asList(foo);
// or
Iterable<Integer> iterable = Arrays.asList(foo);

尽管您需要使用 Integer 数组(而不是 int 数组)才能使其工作.

Though you need to use an Integer array (not an int array) for this to work.

对于原语，可以使用番石榴:

For primitives, you can use guava:

Iterable<Integer> fooBar = Ints.asList(foo);

<dependency>
    <groupId>com.google.guava</groupId>
    <artifactId>guava</artifactId>
    <version>15.0</version>
    <type>jar</type>
</dependency>

对于带有 lambdas 的 Java8:(灵感来自 Jin Kwon 的回答)

For Java8 with lambdas: (Inspired by Jin Kwon's answer)

final int[] arr = { 1, 2, 3 };
final Iterable<Integer> i1 = () -> Arrays.stream(arr).iterator();
final Iterable<Integer> i2 = () -> IntStream.of(arr).iterator();
final Iterable<Integer> i3 = () -> IntStream.of(arr).boxed().iterator();

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