The comparison between HashMap and Hashtable is a common problem in Java interviews, which is used to test whether the programmers can correctly use collection classes and whether they can use a variety of ideas to solve problems at random. The working principle of HashMap, the comparison between ArrayList and Vector, and this question are the most classic questions about Java Collection Framework. Hashtable is an obsolete collection class that has existed in the Java API for a long time. It was rewritten in Java 4 to implement the Map interface, so it has since become part of the Java Collection Framework. Hashtable and HashMap are asked in Java interviews frequently, and even become the most frequently asked questions in Collection Framework interviews, so don not forget to prepare for any Java interviews.square steel tubing
Through this post, I will show you the difference and similar function between HashTable and HashMap.
What is HashTable and Hash Table
HashTable Class implements a “hash table” that maps keys to corresponding values. Any non-null object can be used as a key or value. In order to successfully store and retrieve objects in hash tables, the object used as keys must implement hashCode and equals methods.
Hash Table is a data structure accessed directly according to the key value. That is, it accesses records by mapping key code values to a location in the table to speed up the search. This mapping function is called a hash function, and the array of records is called a hash table.