Map checks if a key exists

MAP detects if a key exists

map<string,string> map = new hashmap<string,string> ();

When:map<string,string> is known from the Experiment, Map.get ("key") is null when no key or value corresponding to a key is null, and Map.get ("") when a key corresponds to value "" Also for "";

It is visible from the experiment that Map.get (key) is null when only object objects are taken, regardless of whether there is no key in the map or if the value corresponding to a key is null.

When Map<object,string>, the Map.get (key). ToString () error (When a key does not exist or a key is null) can be interpreted as such. NULL for type Object cannot be converted to string type;

Map checks if a key exists