put
Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced.
Return
the previous value associated with key, or null if there was no mapping. (A null return can also indicate that the map previously associated null with key.)
Parameters
key
key with which the specified value is to be associated
value
value to be associated with the specified key
Throws
if the key cannot be compared
if key is null and nulls are not supported