If you’ve been working in Java since 'quite some time', you probably are experienced in using Map objects. One very frequent use-case is to check if a Map contains a value: Get the valueIf the value is null, put an initial value.If isn’t, transform the get value and put the new value into the map under the same key Map<String, Integer> map=new HashMap<>(); // ... Integer value=map.get(key); if (value == null) { map.put(key, 1); } else { map.put(key, ++valu