How does the Set.copyOf() method introduced in Java 10 behave when given a null argument?

Java MCQ: How does the Set.copyOf() method introduced in Java 10 behave when given a null argument?

Answer:

Explanation:

The Set.copyOf() method, introduced in Java 10, throws a NullPointerException when given a null argument. This method creates an unmodifiable copy of the specified set, but it requires that the provided set is non-null. If a null set is passed to Set.copyOf(), the method will throw a NullPointerException to indicate that the operation cannot proceed.

Here’s an example that demonstrates this behavior:

import java.util.Set;

public class SetCopyOfExample {
    public static void main(String[] args) {
        Set<String> originalSet = null;

        // This will throw NullPointerException because the argument is null
        Set<String> copySet = Set.copyOf(originalSet);
    }
}

In this example, the call to Set.copyOf(originalSet) will throw a NullPointerException because originalSet is null. This behavior ensures that only valid, non-null sets can be copied using Set.copyOf().

The Set.copyOf() method is useful for creating unmodifiable views of existing sets, but developers must ensure that the input set is non-null.

Reference links:

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