7.java 8 Map.merge

    public static void main(String[] args) {
        List<Integer> integerList = new ArrayList<>();
        Random random = new Random();
        for (int i = 0; i < 100; i++) {
            integerList.add(random.nextInt(1000));
        }

        Map<String, Integer> result = new HashMap<>();
        for (Integer integer : integerList) {
            String tag = "Even";
            if (integer % 2 == 0) {
                tag = "Odd";
            }
            result.merge(tag, 1, (a, b) -> a + b);
        }

        result.forEach((k, v) -> {
            System.out.println(k + " <-> " + v);
        });

        String key = Collections.max(result.entrySet(), Map.Entry.comparingByValue()).getKey();
        System.out.println(key);
    }

Result:

Even <-> 58
Odd <-> 42
Even