Hashtable in Java
The Hashtable is a legacy implementation of HashMap. It provides a key-value store where the keys are hashed. HashMap performs better than Hashtable.
July 24, 2024 · 2 min read
The Hashtable is a legacy implementation of HashMap. It provides a key-value store where the keys are hashed. HashMap performs better than Hashtable.
Key Properties of Hashtable
The Hashtable is synchronized, meaning it is thread-safe and can be shared between multiple threads.
Hashtable does not allow null keys or values. If you try to add null as a key or value, it will throw a NullPointerException.
public class _1a_Hashtable {
public static void main(String[] args) {
Hashtable<Integer, String> hashtable = new Hashtable<>();
hashtable.put(1, "One");
hashtable.put(2, "Two");
hashtable.put(3, "Three");
// Retrieve a value by its key
String value = hashtable.get(2);
System.out.println("Value for key 2: " + value);
// Remove a key-value pair
hashtable.remove(3);
// Check if a key exists
boolean containsKey = hashtable.containsKey(1);
System.out.println("Hashtable contains key 1: " + containsKey);
// Check if a value exists
boolean containsValue = hashtable.containsValue("Two");
System.out.println("Hashtable contains value 'Two': " + containsValue);
// Get the size of the hashtable
int size = hashtable.size();
System.out.println("Size of hashtable: " + size);
// Check if the hashtable is empty
boolean isEmpty = hashtable.isEmpty();
System.out.println("Is hashtable empty? " + isEmpty);
}
}