static class CountWords {

private String fileName;

public CountWords(String fileName) {

this.fileName = fileName;

}

public Map<String, Integer> getDictionary() {

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

FileInputStream fis = null;

try {

fis = new FileInputStream(fileName); // open the file

int in = 0;

String s = ""; // init a empty word

in = fis.read(); // read one character

while (-1 != in) {

if (Character.isLetter((char) in)) {

s += (char) in; //if get a letter, append to s

} else {

// this branch means an entire word has just been read

if (s.length() > 0) {

// see whether word exists or not

if (dictionary.containsKey(s)) {

// if exist, count++

dictionary.put(s, dictionary.get(s) + 1);

} else {

// if not exist, initiate count of this word with 1

dictionary.put(s, 1);

}

}

s = ""; // reInit a empty word

}

in = fis.read();

}

return dictionary;

} catch (IOException e) {

e.printStackTrace();

} finally {

try {

// you always have to close the I/O streams

fis.close();

} catch (IOException e) {

e.printStackTrace();

}

}

return null;

}

}

public static void main(String[] args) {

// you can replace the filePath with yours

CountWords cw = new CountWords("/Users/lisanaaa/Desktop/words.txt");

Map<String, Integer> dictionary = cw.getDictionary(); // get the words dictionary: {word: frequency}

// we change the map to list for convenient sort

List<Map.Entry<String, Integer>> list = new ArrayList<>(dictionary.entrySet());

// sort by lambda valueComparator

list.sort(Comparator.comparing(

m -> m.getValue())

);

Scanner input = new Scanner(System.in);

int k = input.nextInt();

while (k > list.size()) {

System.out.println("Retype a number, your number is too large");

input = new Scanner(System.in);

k = input.nextInt();

}

for (int i = 0; i < k; i++) {

System.out.println(list.get(list.size() - i - 1));

}

input.close();

}