Null Object Design Pattern

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Aliases 📌: None

Description 📚: The Null Object is a mock object that is used to let programmers handle when or how they will handle something null.

For instance, if we fetch records from a database and some have null attributes, we might not want to handle it if we didn't plan to use the nullable attribute.

Advantages ✅

  • Flexibility

Disadvantages 🚫

  • ???

Notes 📝

  • None

Java Implementation

public interface IPerson {
    String name();
}

record Person(String name) implements IPerson {
}

public class NullPerson implements IPerson {
    @Override
    public String name() {
        return "John Doe";
    }
}

We can code the default behavior however we want:

  • throws an exception (ex: unsupported operation)
  • returns false
  • returns 0
  • returns null
  • returns undefined
  • returns another NullObject
  • ...