Mastering Java: The Ultimate Quiz for 'Thinking in Java'

What does the 'synchronized' keyword ensure?

1. The code runs synchronously

2. The method cannot be accessed by more than one thread at a time

3. Increases the speed of execution

4. None of the above

The correct answer is: The method cannot be accessed by more than one thread at a time

The 'synchronized' keyword does not ensure that the code runs synchronously, but rather it ensures that the method it is applied to cannot be accessed by more than one thread at a time. This means that only one thread can access the method at a given time, preventing any potential conflicts or errors caused by multiple threads accessing the same method simultaneously. Option C is incorrect because the 'synchronized' keyword does not increase the speed of execution, but can actually slow it down due to the need for threads to wait for access to the method. Option D is incorrect, as option B is the correct answer.