java - java ArrayList 中最常见的 n 个单词

Question

我需要在 ArrayList 中找到最常见的单词(n 个单词，因此如果 n = 5，则为最常见的 5 个单词)。

private ArrayList<String> wordList = new ArrayList<String>();


public ArrayList<String> mostOften(int k)
{
    ArrayList<String> lista = new ArrayList<String>();
    Set<String> unique = new HashSet<String>(wordList);
    for (String key : unique) 
        System.out.println(key + ": " + Collections.frequency(wordList, key));

    return lista;
}

该函数需要返回最常见单词的列表，按频率排序。如果两个单词有相同的频率，我需要按字母顺序对它们进行排序。我已经发布了我尝试过的内容，但这只能找到频率，我不知道如何做其余的事情。有什么帮助吗？

Answer 1

public class WordFrequency {

    public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("Hello");
        list.add("Hello");
        list.add("aaaa");
        list.add("aaaa");
        list.add("World");
        list.add("abc");
        list.add("abc");
        list.add("cba");
        list.add("abc");
        list.add("World");
        list.add("abc");
        System.out.println(mostOften(list));
    }

    public static List<Word> mostOften(List<String> words){
        Map<String, Word> wordMap = new HashMap<>();
        for (String word : words) {
            Word currentWord = wordMap.get(word);
            if(currentWord == null) 
                wordMap.put(word, new Word(word, 1));
            else
                currentWord.frequency++;
        }

        List<Word> wordList = new ArrayList<>(wordMap.values());
        wordList.sort(new Comparator<Word>() {
            @Override
            public int compare(Word o1, Word o2) {
                if(o1.frequency == o2.frequency)
                    return o1.word.compareToIgnoreCase(o2.word);

                /* sort words with high frequency first */
                return Integer.compare(o2.frequency, o1.frequency);
            }
        });
        return wordList;
    }


}


public class Word{
    String word;
    int frequency;

    public Word(String word, int total) {
        this.word = word;
        this.frequency = total;
    }

    public String toString(){
        return "[" + word + ", " + frequency + "]";
    }
}