computeIfAbsent<K, V>(map, key, mappingFunction): V
If the specified key is not already associated with a value in this map, attempts to compute
its value using the given mapping function and enters it into this map unless null.
Type Parameters
K
V
Parameters
map: Map<K, V>
map from which to get the key's value or compute and associate
key: K
key for which to get the value or with which the computed value is to be associated
If the specified key is not already associated with a value in this map, attempts to compute its value using the given mapping function and enters it into this map unless null.