How is thread safety implemented in the Hashtable data structure?

In Java, the Hashtable data structure implements thread safety by synchronizing all its public methods. This is achieved using the synchronized keyword in methods, ensuring that only one thread can perform operations on the Hashtable object at any given time.

For example, methods like put(), get(), remove(), and others are declared as synchronized, preventing concurrent access and modification of the internal data structure from multiple threads.

However, such synchronization at the object level reduces parallelism and can become a bottleneck under high thread contention.

Example:

public synchronized V put(K key, V value) {
    // implementation of adding an element
}

In modern applications, ConcurrentHashMap is often used for thread-safe hash tables, providing more efficient concurrent operation through segmentation and finer-grained synchronization.