220k views
0 votes
Implement Hash Table using Java. Also comment lines of code

User Aristona
by
8.5k points

1 Answer

2 votes

Step-by-step explanation:

The Hashtable class implements a hash table, which maps keys to values. Any non-null object can be used as a key or as a value. To successfully store and retrieve objects from a hashtable, the objects used as keys must implement the hashCode method and the equals method.

The java.util.Hashtable class is a class in Java that provides a key-value data structure, similar to the Map interface. It was part of the original Java Collections framework and was introduced in Java 1.0.

However, the Hashtable class has since been considered obsolete and its use is generally discouraged. This is because it was designed prior to the introduction of the Collections framework and does not implement the Map interface, which makes it difficult to use in conjunction with other parts of the framework. In addition, the Hashtable class is synchronized, which can result in slower performance compared to other implementations of the Map interface.

In general, it’s recommended to use the Map interface or one of its implementations (such as HashMap or ConcurrentHashMap) instead of the Hashtable class.

Here’s an example of how to use the Hashtable class:

import java.util.Enumeration;

import java.util.Hashtable;

public class Main {

public static void main(String[] args) {

Hashtable<String, Integer> hashtable = new Hashtable<>();

// Adding elements to the hashtable

hashtable.put("A", 1);

hashtable.put("B", 2);

hashtable.put("C", 3);

// Getting values from the hashtable

int valueA = hashtable.get("A");

System.out.println("Value of A: " + valueA);

// Removing elements from the hashtable

hashtable.remove("B");

// Enumerating the elements of the hashtable

Enumeration<String> keys = hashtable.keys();

while (keys.hasMoreElements()) {

String key = keys.nextElement();

System.out.println("Key: " + key + ", Value: " + hashtable.get(key));

}

}

}

Output

Value of A: 1

Key: A, Value: 1

Key: C, Value: 3

In conclusion, while the Hashtable class still exists in Java and can still be used, it’s generally recommended to use the Map interface or one of its implementations instead.

User Mylene
by
7.3k points