How is data consistency ensured when working with parallel threads or processes?

To ensure data consistency when working with parallel threads or processes in Android (and Java in general), the following approaches are used:

• Synchronization (synchronized) — locking critical sections of code so that only one thread can execute them at a time.

• Using thread-safe collections — for example, ConcurrentHashMap, CopyOnWriteArrayList.

• Volatile variables — guarantee visibility of changes to a variable across threads.

• Lock and ReentrantLock — more flexible locking mechanisms.

• Using atomic classes from java.util.concurrent.atomic (e.g., AtomicInteger) for lock-free operations.

• Architectural solutions — for example, using message queues, Handler, LiveData, ViewModel, which help manage state and updates in the UI thread.

Example of synchronization:

private int counter = 0;

public synchronized void increment() {
    counter++;
}

Thus, to avoid race conditions and ensure consistency, it is necessary to correctly choose and apply synchronization mechanisms and thread-safe structures.