java.util.concurrent.atomic

The java.util.concurrent.atomic package in Java provides a set of classes that support lock-free, thread-safe operations on single variables. These classes are crucial for performance-sensitive applications where high concurrency is involved, as they allow multiple threads to operate on shared data without using explicit synchronization.

Core Classes

1. AtomicBoolean: A boolean value that may be updated atomically.
2. AtomicInteger: An integer value that may be updated atomically.
3. AtomicLong: A long integer value that may be updated atomically.
4. AtomicReference: A reference to an object that may be updated atomically.
5. AtomicIntegerArray: An array of integers where elements can be updated atomically.
6. AtomicLongArray: An array of long integers where elements can be updated atomically.
7. AtomicReferenceArray: An array of references where elements can be updated atomically.

These classes use low-level atomic machine instructions to ensure that operations on the variables are atomic, meaning they are indivisible and completed without interruption.