【算法】计算一篇文章的单词数（C、Java语言实现）

1. C语言：一个字符一个字符的读取

（有空再贴出来）

2.Java语言：按行读取，并用正则分割成多个单词，再用MapReduce并行计算单词数 (我使用的是ieda，有些地方跟eclipse有点区别)

/**
     * 按流读取文件 (通过read.readLine()获取一行)
     * @param path
     * @return
     * @throws FileNotFoundException
     */
    public BufferedReader openFile(final String path) throws FileNotFoundException {
        BufferedReader reader = new BufferedReader(new FileReader(path));
 
        return reader;
    }

/**
     * 采用Hash计算单词数
     * @param line
     * @return
     */
    public void hash(final HashMap<String, Integer> hashMap, final String line) {
        // 不能分割b2c,it's这类单词
        String[] words = line.split("[^a-z]+");
 
        for (String word : words) {
            // 去除空格、空行
            if (word.length() > 0) {
                if (hashMap.containsKey(word) == false) {
                    hashMap.put(word, 1);
                }
            }
        }
    }

/**
     * 计算单词个数
     * @param hashMap
     * @return
     */
    public Integer computeWordCount(final HashMap<String, Integer> hashMap) {
        return hashMap.size();
    }

测试用例：

public static void main(String args[]) throws IOException {
        String path = Paths.get(PROJECT_ROOT_DIR, "src/main/resources/articles/test.txt").toString();
        BufferedReader reader = openFile(path);
 
        HashMap<String, Integer> hashMap = new HashMap<>();
        String line;
        int wordCount;
 
        while((line = reader.readLine()) != null) {
            hash(hashMap, line);
        }
 
        wordCount = computeWordCount(hashMap);
        System.out.println(wordCount);
    }