Does the standard HashMap implementation provide safe operation in a multithreaded environment?

The standard implementation of HashMap in Java is not thread-safe. This means that when accessed concurrently from multiple threads without external synchronization, issues such as data corruption or incorrect behavior can occur.

If a thread-safe implementation is needed, you can use:

• ConcurrentHashMap — optimized for multi-threaded operation without full locking.
• The wrapper Collections.synchronizedMap(new HashMap<>()) — provides synchronization but with coarser locking.

Example of using ConcurrentHashMap:

import java.util.concurrent.ConcurrentHashMap;

ConcurrentHashMap<String, Integer> map = new ConcurrentHashMap<>();
map.put("key", 1);
Integer value = map.get("key");

Thus, for safe operation in a multi-threaded environment, the standard HashMap should not be used without additional synchronization.