什么是番石榴相当于Scala的flatMap？

Question

Looking through https://github.com/google/guava/wiki/FunctionalExplained I see operations like transform , which will transform a list but keep the same cardinality. How can I perform a transform that results in a different cardinality? eg (pseudocode) List(1,2,3).transform(i => List(i, i)) -> List(1,1,2,2,3,3)

Answer 1

截至13版，有transformAndConcat上FluentIterable 。

Answer 2

我不认为有直接的翻译，但是concat后面的transform应该是等价的。

Answer 3

In Eclipse Collections , collect() is the equivalent of Scala's map() , and flatCollect() is the equivalent of Scala's flatMap() .

Here is an example usage of flatCollect with Java 8 Lambdas .

Note: I am a committer for Eclipse Collections.

Answer 4

Pay attention to one thing, though: Scala's map methods return new collections, while the transform() method in Guava returns a transformed view of the original collection. This is a very subtle difference. You need to decide whether the 'view over original collection' is appropriate for your context.