如何在Java流中使用thenComparing [英] How to use thenComparing in java stream

问题描述

我有一个以字符串为值的映射.我想首先按长度排序，如果字符串的长度相同，我想按字母排序. 我写了那些代码:

I have a map with strings as values. I want to sort it firstly by length, and if length of the strings is the same, i want to sort it alphabetic. I wrote those code :

String out = outMap.values().stream()
                .sorted(Comparator.comparing(e -> e.length()).thenComparing()...)
                .collect(Collectors.joining());

问题是，当我写thenComparing时，我不能再使用e.length().我该如何解决?

The problem is, when i am writing thenComparing, I couldn't use e.length() anymore. How can i fix it?

Map<Character, String>.我想对所有字符串进行排序，并通过输出使所有字符串成为一个字符串.

EDIT : Map<Character, String> . I want to sort the strings and make one string in output by concat all of them.

推荐答案

如何

String out = outMap.values().stream()
        .sorted(Comparator.comparingInt(String::length)
                          .thenComparing(Comparator.naturalOrder()))
                    //OR  .thenComparing(String.CASE_INSENSITIVE_ORDER))
        .collect(Collectors.joining());

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