The Objects.requireNonNullElse method, introduced in Java 9, provides a safe and convenient way to handle null references by returning a default value if the provided object is null. This method ensures that you won’t get a NullPointerException in cases where you expect an object but want a fallback when it’s null.

Syntax

public static <T> T requireNonNullElse(T obj, T defaultObj)

Parameters

• obj: The object to check for null.
• defaultObj: The object to return if obj is null. This cannot be null; otherwise, a NullPointerException will be thrown.

Returns

• If obj is not null, it returns obj.
• If obj is null, it returns defaultObj.

Key Features

• Ensures defaultObj is never null. If you pass a null defaultObj, the code will throw a NullPointerException.
• Useful when you want a non-null value without writing explicit if-else conditions.

---

Example Usage

import java.util.Objects;

public class Main {
    public static void main(String[] args) {
        String value = null;
        String defaultValue = "Default Value";

        // Using Objects.requireNonNullElse
        String result = Objects.requireNonNullElse(value, defaultValue);

        // Prints: Default Value
        System.out.println(result);

        // If value is not null
        value = "Actual Value";

        // Prints: Actual Value
        System.out.println(Objects.requireNonNullElse(value, defaultValue));
    }
}

How It Works

1. When value is null, Objects.requireNonNullElse(value, defaultValue) will safely return "Default Value".
2. When value is not null, it returns the actual value of value.

---

Important Notes

1. defaultObj cannot be null:
   If the defaultObj provided is null, the method will throw a NullPointerException. For example:

   String result = Objects.requireNonNullElse(null, null); // Throws NullPointerException
   

2. Use for Non-Primitive Types Only:
   Since Objects.requireNonNullElse works only with reference types (i.e., not primitive types like int, double), use boxed primitives such as Integer, Double, etc., when needed.

   // Example with Integer:
   Integer number = null;
   Integer defaultNumber = 42;
   
   Integer result = Objects.requireNonNullElse(number, defaultNumber);
   
   // Prints: 42
   System.out.println(result);
   

---

Using Objects.requireNonNullElse is a clean, concise, and safe way to provide fallback values for potentially null objects without the need for verbose checks.