Lambda填充地图 [英] Lambda to populate Map

问题描述

我正在尝试用字词及其出现次数填充地图。我正在尝试编写一个lambda来执行此操作，如下所示：

I am trying to fill up a map with words and the number of their occurrences. I am trying to write a lambda to do it, like so:

Consumer<String> wordCount = word -> map.computeIfAbsent(word, (w) -> (new Integer(1) + 1).intValue());

map 是 Map< String，Integer> 。它应该只是将地图中的单词作为键插入，如果它不存在，如果它存在，它应该将其整数值增加1.这一个在语法方面是不正确的。

map is Map<String, Integer>. It should just insert the word in the map as a key if it is absent and if it is present it should increase its integer value by 1. This one is not correct syntax-wise.

推荐答案

您不能使用 computeIfAbsent 递增计数，因为它只会在第一次计算。

You can't increment the count using computeIfAbsent, since it will only be computed the first time.

你可能意味着：

map.compute(word, (w, i) -> i == null ? 1 : i + 1);

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