Counting occurrences of a key in a Map in Java

Question

I\'m writing a project that captures Java keywords from a .java file and keeps track of the occurrences with a map. I\'ve used a similar method in the past successfully, but

Answer 1

Even more concise using Map.merge() (since Java 8):

if (keywordSet.contains(key)) {
    map.merge(key, 1, (currentCount, notUsed) -> ++currentCount);
}

Here is a generic implementation of a counting map - a map with values representing the count of their keys:

public static  void count(K key, Map map) {
    map.merge(key, 1, (currentCount, notUsed) -> ++currentCount);
}

public static void main(String[] args) {
    Map map = new HashMap<>();
    count("A", map);
    count("B", map);
    count("A", map);
    count("Z", map);
    count("A", map);
    System.out.println(map); // {A=3, B=1, Z=1}
}