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In Java, HashMap and Hashtable are two commonly used data structures for storing and retrieving key-value pairs. Both data structures implement the Map interface and provide similar functionality, but there are some important differences between them. In this article, we will explore the difference between HashMap and Hashtable and their implementations in detail.<\/p>\n
HashMap is java.util package class that implements the Map interface. It stores key-value pairs in a hash table, which allows for fast retrieval and insertion of elements. A HashMap does not guarantee the order of its elements and allows null values for both keys and values.<\/p>\n
The initial capacity of a HashMap is 16, and its load factor is 0.75 by default. If the number of entries exceeds the product of the load factor and current capacity, the current capacity is increased and all entries are rehashed for uniform distribution.<\/p>\n
To learn more, refer to the articles:<\/p>\n
Hashtable is also java.util package class that implements the Map interface. It stores key-value pairs in a hash table, which allows for fast retrieval and insertion of elements. A Hashtable does not guarantee the order of its elements and does not allow null values for keys or values.<\/p>\n
The initial capacity of a Hashtable is 11, and its load factor is 0.75 by default. When the number of entries exceeds the product of the load factor and current capacity, capacity is increased and entries are rehashed to ensure uniform distribution.<\/p>\n
Let us now discuss the difference between HashMap and Hashtable.<\/p>\n
Thread Safety<\/strong> Null Values<\/strong> Performance<\/strong> Iteration Order<\/strong> Initial Capacity<\/strong> Load Factor<\/strong> Enumeration<\/strong> Let us see some Java code to show the difference between HashMap and Hashtable.<\/p>\n Example 1 of the Difference between HashMap and Hashtable<\/strong> Code:<\/strong><\/p>\n\t\t\t\t\t\t
\nHashtable is thread-safe, which means that multiple threads can access it simultaneously without any issues. On the other hand, HashMap is not thread-safe and can cause problems if accessed by multiple threads at the same time.<\/p>\n<\/li>\n
\nHashtable does not allow null values for keys or values, whereas HashMap allows null values for both keys and values.<\/p>\n<\/li>\n
\nHashMap is generally faster than Hashtable because it is not synchronized. However, if thread safety is required, Hashtable can still be faster than a synchronized HashMap.<\/p>\n<\/li>\n
\nHashMap does not guarantee the order of its elements, whereas Hashtable iterates through its elements in the order they were inserted.<\/p>\n<\/li>\n
\nHashMap has an initial capacity of 16, whereas Hashtable has an initial capacity of 11.<\/p>\n<\/li>\n
\nHashMap has a default load factor of 0.75, whereas Hashtable also has a default load factor of 0.75.<\/p>\n<\/li>\n
\nHashtable uses an Enumeration to iterate through its elements, whereas HashMap uses an Iterator.<\/p>\n<\/li>\n<\/ul>\nExamples to Demonstrate the Difference between HashMap and Hashtable<\/h2>\n
\nThis Java Code shows how null values are handled by HashMap and Hashtable.<\/p>\n