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。我希望有一个方法来做到这一点,但他们最近的方法是,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。
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]
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