What difficulties can arise when working with multiple threads simultaneously?

When working with multiple threads simultaneously, the following difficulties may arise:

• Race conditions: when several threads access and modify shared data at the same time, leading to unpredictable results.
• Deadlocks: situations where two or more threads wait for each other, blocking execution.
• Data inconsistency: without proper synchronization, data can become corrupted.
• Visibility issues: changes made in one thread may not be immediately visible to others.

To address these problems, Java uses synchronization mechanisms such as the synchronized keyword, classes from the java.util.concurrent package (e.g., ReentrantLock, AtomicInteger), and volatile variables.

Example of using synchronized:

public class Counter {
    private int count = 0;

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

    public synchronized int getCount() {
        return count;
    }
}