Can you explain what class thread safety means and why it is important?

Thread safety of a class means that its methods and state work correctly when accessed concurrently from multiple threads without errors, data races, or inconsistent states.

This is important because in multithreaded applications, multiple threads may modify the same data simultaneously. If a class is not thread-safe, it can lead to unpredictable behavior, crashes, or data corruption.

Various approaches are used to ensure thread safety:

• Synchronization (e.g., the synchronized keyword in Java) for sequential access.
• Use of thread-safe collections and classes from java.util.concurrent.
• Immutability — creating immutable objects.

Example of a thread-safe counter:

public class SafeCounter {
    private int count = 0;

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

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

Here, methods are synchronized to prevent concurrent modification of the count variable by multiple threads.