Cracking Coding Interview - 16.2 Word Frequencies

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Map<String, Integer> cache = new HashMap<>();

public void prepare() {  
  File book = ...;
  while (book not eof) {
    String line = book.readLine();
    String[] words = line.split("[^\\w]");
    for (String word : words) {
      if (!cache.contains(word)) {
        cache.put(word, 0);
      }
      cache.put(word, cache.get(word) + 1);
    }
  }
}

public int wordFreq(String word) {
  if (!cache.contains(word)) {
    cache.put(word, 0);
  }
  return cache.get(word);
}