库方法通过谓词分割集合 [英] Library method to partition a collection by a predicate

问题描述

我有一个对象集合，我想分区成两个集合，其中一个传递一个谓词，其中一个失败的谓词。我希望有一个 Guava 方法来做到这一点，但他们最近的方法是过滤器，它不给我其他集合。

I have a collection of objects that I would like to partition into two collections, one of which passes a predicate and one of which fails a predicate. I was hoping there would be a Guava method to do this, but the closest they come is filter, which doesn't give me the other collection.

我会形象的方法的签名将是这样： p>

I would image the signature of the method would be something like this:

public static <E> Pair<Collection<E>, Collection<E>> partition(Collection<E> source, Predicate<? super E> predicate)

快速代码自己，但我正在寻找一个现有的库方法，做我想要的。

I realize this is super fast to code myself, but I'm looking for an existing library method that does what I want.

推荐答案

使用Guava的 Multimaps.index 。

Use Guava's Multimaps.index.

的单词分为两部分：长度大于3的那些和不大于3的那些。

Here is an example, which partitions a list of words into two parts: those which have length > 3 and those that don't.

List<String> words = Arrays.asList("foo", "bar", "hello", "world");

ImmutableListMultimap<Boolean, String> partitionedMap = Multimaps.index(words, new Function<String, Boolean>(){
    @Override
    public Boolean apply(String input) {
        return input.length() > 3;
    }
});
System.out.println(partitionedMap);

列印：

false=[foo, bar], true=[hello, world]

这篇关于库方法通过谓词分割集合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！