Java 8 FAQ: Top Questions

The Optional class in Java 8 is a container object used to represent the presence or absence of a value. It helps avoid null pointer exceptions by providing methods that safely handle values that may be missing.

🗺️ Step-by-Step Instructions:

1. Wrap your potentially-null object with Optional.ofNullable().
2. Use isPresent() or ifPresent() to check and act on the value.
3. Use orElse() or orElseGet() to provide fallback values.
4. Use map() and flatMap() for safe transformations.

📥 Example Input:

String name = null;
Optional optionalName = Optional.ofNullable(name);

🏆 Expected Output:

Anonymous

✅ Java 8 Solution:

import java.util.Optional;

public class OptionalExample {
  public static void main(String[] args) {
    String name = null;

    Optional optionalName = Optional.ofNullable(name);
    String result = optionalName.orElse("Anonymous");

    System.out.println(result);
  }
}

📘 Detailed Explanation:

• ofNullable(): Creates an Optional that may hold a null.
• orElse(): Returns the value if present or a default value.
• orElseGet(): Uses a Supplier to generate a fallback.
• map(): Applies a function if the value is present.
• flatMap(): Used when mapping returns another Optional.

🛠️ Use Cases:

• Returning safe results from repository or config lookups.
• Handling optional form inputs or user data fields.
• Reducing explicit null checks across the codebase.