Question : In Java, what is the main purpose of the synchronized keyword?

A ) To declare that a method can only be accessed by one thread at a time.

B ) To create a new thread in a multithreaded environment.

C ) To allow static methods to be executed in parallel without causing data inconsistency.

D ) To enable the automatic garbage collection of objects in memory.

The correct option is : A

Reason : This option is correct because the synchronized keyword is a fundamental construct in Java that ensures only one thread can execute a synchronized method or block at any given time. This effectively prevents concurrent access to the same section of code or shared resource, thus maintaining data integrity and preventing inconsistencies that could arise from simultaneous write operations by multiple threads.

Explanation about incorrect options :

option B : this option is incorrect because the synchronized keyword does not create a new thread. Instead, it is used to control access to a method or block of code by multiple existing threads. If you want to create a new thread, you would typically use the Thread class or implement the Runnable interface, where synchronization would be applied separately if needed to control access to shared resources.

option C : this option is incorrect because synchronized methods or blocks do not allow static methods to execute in parallel without data inconsistency. In fact, synchronized static methods require a class-level lock, meaning that only one thread can execute any synchronized static method of that class at a time. If multiple threads attempt to access different static synchronized methods, they will still be blocked from entering any synchronized methods until the lock is released, hence just mitigating data inconsistency, not allowing parallel execution.

option D : this option is incorrect because the synchronized keyword does not have any association with garbage collection in Java. Garbage collection is handled automatically by the Java Virtual Machine (JVM) and operates independently from thread synchronization mechanisms. The synchronized keyword is specifically focused on controlling access to code blocks or methods among multiple threads, while garbage collection manages memory and object lifecycle, reclaiming memory from objects that are no longer in use.