Which of the following is true about the Map.ofEntries() method in Java 9?

Java MCQ: Which of the following is true about the Map.ofEntries() method in Java 9?

Answer:

Explanation:

The Map.ofEntries() method in Java 9 allows the creation of an immutable map with more than 10 entries. Unlike Map.of(), which is limited to a fixed number of entries, Map.ofEntries() is more flexible and suitable for creating maps with a larger number of key-value pairs.

Here’s an example of using Map.ofEntries():

import java.util.Map;
import java.util.Map.Entry;

public class MapOfEntriesExample {
    public static void main(String[] args) {
        Map<String, Integer> ages = Map.ofEntries(
            Entry.of("John", 25),
            Entry.of("Jane", 30),
            Entry.of("Jack", 22),
            Entry.of("Doe", 35)
        );
        System.out.println(ages);

        // This will throw UnsupportedOperationException because the map is immutable
        // ages.put("Alice", 40);
    }
}

In this example, Map.ofEntries() creates an immutable map with four key-value pairs. The map cannot be modified after creation, and any attempt to do so (e.g., using put()) will result in an UnsupportedOperationException.

Map.ofEntries() is particularly useful when you need to create an immutable map with a larger number of entries, providing a concise and efficient way to do so.

Reference links:

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