albertattard / domain-primitives-api

Domain Objects API

Domain Primitives API

Name	Sate
CircleCI
SonarQube

This project provides a set of base classes that can be used when building domain primitives. The base classes come into three flavours:

1. lang
2. optional
3. mandatory

The lang set of base classes represents domain primitives that are based on the Java primitives, such as int and long. The optional and mandatory set of base classes represents options such as Integer or String, where the optional version allows nulls while the mandatory peer does not allow nulls.

For example, say we have a class that has two fields, title and name. The title field is optional while the name field is mandatory,

public class Person {
  private final PersonTitle title;
  private final PersonName name;

}

The Person uses two domain primitive classes, the PersonTitle and the PersonName. The PersonTitle should accept nulls and thus it is optional.

import java.util.Optional;
import com.google.common.base.Preconditions;

import com.javacreed.api.domain.primitives.optional.StringBasedDomainPrimitive;

public class PersonTitle extends StringBasedDomainPrimitive {

    private static final PersonTitle EMPTY = new PersonTitle(Optional.empty());

    public static PersonTitle empty() {
        return EMPTY;
    }

    public static PersonTitle ofNullable(String value) {
        if(value == null){
            return empty();
        }

        return of(value);
    }

    public static PersonTitle of(String value) throws NullPointerException {
        Preconditions.checkNotNull(value);
        return new PersonTitle(Optional.of(value));
    }

    private PersonTitle(Optional<String> value) {
        super(value);
    }
}

The PersonName class, on the other hand, is mandatory.

import com.google.common.base.Preconditions;

import com.javacreed.api.domain.primitives.mandatory.StringBasedDomainPrimitive;

public class PersonName extends StringBasedDomainPrimitive {

    public static PersonName of(String value) throws NullPointerException {
        Preconditions.checkNotNull(value);
        return new PersonName(value);
    }

    private PersonName(String value) {
        super(value);
    }
}

Will add more to this page later on.