Which of the following is true about the ‘volatile’ keyword in Java?

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Java MCQ: Which of the following is true about the ‘volatile’ keyword in Java?

a) It ensures that a variable’s value is read from main memory, not from a thread’s local cache
b) It prevents multiple threads from accessing a variable simultaneously
c) It guarantees that a variable cannot be modified
d) It is used to create immutable objects

Answer:

a) It ensures that a variable’s value is read from main memory, not from a thread’s local cache

Explanation:

The volatile keyword in Java is used to indicate that a variable’s value will be modified by different threads. It ensures that the value of the variable is always read from and written to the main memory, rather than being cached in a thread’s local cache. This ensures visibility of changes made to the variable across all threads.

However, volatile does not provide atomicity, meaning that operations on volatile variables are not guaranteed to be thread-safe. For atomicity, other mechanisms like synchronized blocks or atomic classes from the java.util.concurrent package should be used.

Understanding the volatile keyword is important for managing concurrency in Java, especially when dealing with variables shared between multiple threads.

Reference links:

https://www.rameshfadatare.com/learn-java-programming/
https://www.javaguides.net/p/java-tutorial-learn-java-programming.html

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