What are the easiest methods you can use to ensure data consistency between threads?

To ensure data consistency between threads in Java, several simple methods can be used:

• The volatile keyword — guarantees that changes to a variable are immediately visible to all threads, without caching.
• Synchronized blocks (synchronized) — provide mutual exclusion when accessing shared resources.
• Using atomic classes from java.util.concurrent.atomic — for example, AtomicInteger, which provide atomic operations without locks.

Example with volatile:

volatile boolean flag = false;

// Thread 1
flag = true;

// Thread 2
if (flag) {
    // will see the updated value
}

These methods are simple and effective for basic synchronization and data consistency.