What is the purpose of the Java 9 List.of() method?

Java MCQ: What is the purpose of the Java 9 List.of() method?

Answer:

Explanation:

The List.of() method introduced in Java 9 is used to create an immutable List. An immutable list is a list that cannot be modified after it is created, meaning that no elements can be added, removed, or changed.

Here’s an example of using List.of():

import java.util.List;

public class ListOfExample {
    public static void main(String[] args) {
        List<String> names = List.of("John", "Jane", "Jack");
        System.out.println(names);

        // This will throw UnsupportedOperationException because the list is immutable
        // names.add("Doe");
    }
}

In this example, List.of("John", "Jane", "Jack") creates an immutable list containing three elements. Any attempt to modify the list (e.g., adding or removing elements) will result in an UnsupportedOperationException.

List.of() is particularly useful for creating small, fixed collections of elements where immutability is desired, ensuring that the list remains constant throughout its lifetime.

Reference links:

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