HashtableContains

Hashtable.contains(Object) and ConcurrentHashMap.contains(Object) are legacy methods for testing if the given object is a value in the hash table. They are often mistaken for containsKey, which checks whether the given object is a key in the hash table.

If you intended to check whether the given object is a key in the hash table, use containsKey instead. If you really intended to check whether the given object is a value in the hash table, use containsValue for clarity.