hashtable allow duplicate keys

Note: The following source code is based on jdk1.7.0 _ 11 I analyzed the source code of hashmap in the previous article. I believe everyone has a deeper understanding of hashmap. This article introduces another common class of map set, hashtable.

Hashtable and HashMap are fairly easy to ask in the Java interview, and even become the most frequently asked questions in the collection framework interview, so don't forget to prepare the question before you take any Java interview.Let's first

Linear tables, linked lists, and hash tables are common data structures. During Java Development, JDK provides a series of corresponding classes for us to implement basic data structures. These classes are in the Java. util package. This article

Guide:1 HashMap is not thread-safeHashMap is an interface that is a sub-interface of the map interface, an object that maps keys to values, where the keys and values are objects and cannot contain duplicate keys, but can contain duplicate values.

Differences between Map and HashMap, Hashtable, and HashSet in Java, hashmaphashsetHashMap and Hashtable both implement the Map interface, both save the K-V pair (key-value Pair); HashSet implements the Set interface, the nature is similar to the

HashMap, HashTable, TreeMap difference and usage, hashmaptreemap When I started learning HashTable, HashMap and TreeMap, I was dizzy and felt that the role was similar. However, I found many differences in practical use. You must note that the

Guidance: 1 hashmap is NOT thread-safe Hastmap is a sub-interface of the map interface. It is an object that maps keys to values. The key and value types are all objects and cannot contain duplicate keys, but can contain duplicate values.

The difference between HashMap, HashSet, and Hashtable is a common interview topic for Java programmers, which is only recorded in this blog and is thoroughly analyzed in the source code:Before the analysis, the difference is listed below1:hashset

Just beginning to see HASHTABLE,HASHMAP and TreeMap when more dizzy, feel the role of almost, but to the actual use of time and found there are many differences. So I searched some relevant information to learn, the following is my study

First, set and map relationshipsThe set represents an unordered collection element, a collection of elements that are not repeatable, and a map that represents a collection of multiple key-value, and the map collection is the extension of the set