Introduction HashMap in Java is a Map based collection class that is used for storing Key & value pairs, it is denoted as HashMap<K, V>. It is similar to the Hashtable class except that it is unsynchronized and permits nulls (null values and null key). It is not an ordered [...]
HashMap and Hashtable both are used to store data in key and value form. Both are using hashing technique to store unique keys. Differences between HashMap and Hashtable: Hashtable is synchronized, whereas HashMap is not. This makes HashMap better for non-threaded applications, as unsynchronized Objects typically perform better than synchronized [...]