Question

我已将文件中的字符串存储到ArrayList中，并使用HashSet计算每个字符串的出现次数。

我希望列出前5个单词及其出现次数。我应该能够实现这个，而不是实现哈希表，树形图等。我怎样才能实现这个目标？

这是我的ArrayList：

List<String> word_list = new ArrayList<String>();

        while (INPUT_TEXT1.hasNext()) {
            String input_word = INPUT_TEXT1.next();
            word_list.add(input_word);

        }

        INPUT_TEXT1.close();

        int word_list_length = word_list.size();



        System.out.println("There are " + word_list_length + " words in the .txt file");
        System.out.println("\n\n");

        System.out.println("word_list's elements are: ");



        for (int i = 0; i<word_list.size(); i++) {
                System.out.print(word_list.get(i) + "  ");

            }

        System.out.println("\n\n");

这是我的HashSet：

Set<String> unique_word = new HashSet<String>(word_list);

    int number_of_unique = unique_word.size();

    System.out.println("unique worlds are: ");

    for (String e : unique_word) {
        System.out.print(e + " ");

    }

    System.out.println("\n\n");


    String [] word = new String[number_of_unique];
    int [] freq = new int[number_of_unique];

    int count = 0;

    System.out.println("Frequency counts : ");

    for (String e : unique_word) {
        word[count] = e;
        freq[count] = Collections.frequency(word_list, e);



        System.out.println(word[count] + " : "+ freq[count] + " time(s)");
        count++;

    }

难道我正在推翻一步吗？提前致谢

Answer 1

您可以使用HashMap（包含唯一字key，频率为value），然后按照相反的顺序对values进行排序，如下所示：以下步骤：

（1）用{/ p>加载word_list

（2）从word_list

中找到唯一的单词

（3）将唯一字词存储到HashMap，其中唯一字为key，频率为value

（4）将HashMap与值（频率）

排序

您可以参考以下代码：

public static void main(String[] args) {

        List<String> word_list = new ArrayList<>();
        //Load your words to the word_list here

        //Find the unique words now from list
        String[] uniqueWords = word_list.stream().distinct().
                                       toArray(size -> new String[size]);
        Map<String, Integer> wordsMap = new HashMap<>();
        int frequency = 0;

        //Load the words to Map with each uniqueword as Key and frequency as Value
        for (String uniqueWord : uniqueWords) {
            frequency = Collections.frequency(word_list, uniqueWord);
            System.out.println(uniqueWord+" occured "+frequency+" times");
            wordsMap.put(uniqueWord, frequency);
        }

       //Now, Sort the words with the reverse order of frequency(value of HashMap)
       Stream<Entry<String, Integer>> topWords = wordsMap.entrySet().stream().
         sorted(Map.Entry.<String,Integer>comparingByValue().reversed()).limit(5);

        //Now print the Top 5 words to console
        System.out.println("Top 5 Words:::");
        topWords.forEach(System.out::println);
 }

Answer 2

使用java 8并将所有代码放在一个块中。

 Stream<Map.Entry<String,Long>> topWords =
            words.stream()
                    .map(String::toLowerCase)
                    .collect(groupingBy(identity(), counting()))
                    .entrySet().stream()
                    .sorted(Map.Entry.<String, Long> comparingByValue(reverseOrder())
                            .thenComparing(Map.Entry.comparingByKey()))
                    .limit(5);

迭代流

topWords.forEach(m -> {
            System.out.print(m.getKey() + " : "+ m.getValue() + "time(s)");
        });

从文本文件中排序字符串出现次数

2 个答案: