Using Hashtable in Different Programming Languages

Implementing Hashtables in Different Languages

Different programming languages provide built-in implementations of Hashtables.

Language	API (Hashtable Implementation)
Java	java.util.HashMap
Python	dict
C++	std::unordered_map
JavaScript	Object or Map
C#	Dictionary<TKey, TValue>
Go	map

Code Examples

java

import java.util.HashMap;

public class Solution {
    public static void main(String[] args) {
        // Creating a Hashtable using HashMap
        HashMap<String, Integer> scores = new HashMap<>();

        // Adding key-value pairs
        scores.put("Alice", 85);
        scores.put("Bob", 92);
        scores.put("Charlie", 78);

        // Retrieving values
        System.out.println("Alice's Score: " + scores.get("Alice")); // Output: 85
    }
}

Limitations of Hashtables

Although Hashtables are incredibly fast and efficient, they come with some drawbacks.

Limitation	Explanation
High Memory Usage	Hashtables require extra memory to store keys, values, and handle collisions.
No Ordering	Unlike arrays or linked lists, Hashtables do not maintain insertion order.
Performance Degradation	If too many collisions occur, lookup time can degrade from O(1) to O(n).
Resizing Cost	When resizing occurs, all elements need to be rehased, causing a temporary slowdown.

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← Hashing, Collisions, Overflow, and Introduction to HashSets →