Java 8 Stream数组中的唯一字符

本文介绍了Java 8 Stream数组中的唯一字符的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

尝试编写一个简单的程序，该程序将在 Java8 中从输入数组中打印出唯一的单词.例如，如果输入为

Trying to write a simple program that will print the unique words from an input array in Java8 . For example if the input is

String[] input = {"This", "is", "This", "not"};

程序应输出[T, h, i, s, n, o, t]，元素的顺序应与输入中出现的顺序相同.我的方法是先输入split，然后是map，distinct，最后是collect到列表.但是下面的代码是打印流而不是单词的列表，我想念的是什么?例如.

The program should output [T, h, i, s, n, o, t] , the order of elements should follow the same pattern as they appear in input. My approach is to split the input , then map, distinct and finally collect it toList. But the following code is printing list of streams instead of words, what am i missing?.E.g.

String[] input = {"This", "is", "This", "not"}; System.out.println(Arrays.stream(input) .map(word -> word.split("")) .map(Arrays::stream) .distinct() .collect(toList()));

当前输出

[java.util.stream.ReferencePipeline$Head@548c4f57, java.util.stream.ReferencePipeline$Head@1218025c, java.util.stream.ReferencePipeline$Head@816f27d, java.util.stream.ReferencePipeline$Head@87aac27]

我很想看看Java8中是否还有其他方法可以达到相同的目的.

I am interested to see if there are some other ways in Java8 to achieve the same.

推荐答案

您需要使用 flatMap 以便与流的内容进行映射.正如您所注意到的，Arrays::stream生成单独的流，而您想要的是将所有这些流展平为单个流，例如.

You need to use flatMap in order to map with the content of the stream . As you noticed that Arrays::stream generate separate streams and what you want is to flatten all those streams into single stream E.g.

System.out.println(Stream.of(input) .map(w -> w.split("")) .flatMap(Arrays::stream) .distinct() .collect(Collectors.toList()));

输出

[T, h, i, s, n, o, t]