In which situations should the synchronized keyword be used in a programming language to ensure thread safety?

The synchronized keyword in Java is used to ensure thread safety when accessing shared resources concurrently. It guarantees that only one thread can execute a specific block of code or method at a time.

Use synchronized in the following situations:

• When modifying shared data or states that can be accessed by multiple threads.
• When working with shared resources, such as collections, files, databases.
• To prevent data races and ensure atomicity of operations.

Example of using synchronized:

public class Counter {
    private int count = 0;

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

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

Here, the increment and getCount methods are synchronized to prevent concurrent modification and reading of the count variable from different threads.