计算 ArrayList 中单词的出现次数 [英] Count occurrences of words in ArrayList

问题描述

我有一个 ArrayList 包含重复条目的单词.

I have an ArrayList of words with duplicate entries.

我想计算并保存数据结构中每个单词的出现次数.

I want to count and save occurrences for each word in a data structure.

我该怎么做?

推荐答案

如果你没有大量的字符串，实现它的最短方法是使用 Collections.frequency 方法，比如这个:

If you don't have a huge list of strings the shortest way to implement it is by using Collections.frequency method, like this:

List<String> list = new ArrayList<String>();
list.add("aaa");
list.add("bbb");
list.add("aaa");

Set<String> unique = new HashSet<String>(list);
for (String key : unique) {
    System.out.println(key + ": " + Collections.frequency(list, key));
}

输出:

aaa: 2
bbb: 1

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