Java Compatibility

Java classes are different from those of Kotlin. The main difference for Mappie is that Java does not have the concept of properties. Instead, the convention is to have a field x, and a getter getX() and setter setX(Person value) method.

Mappie uses these getter- and setter methods in implicit mappings. They must follow the convention getX() and setX(...) for the property x to be inferred. Also note that in Java all types are nullable. Mappie will give a warning if a Java type is used to assign to a non-nullable target. The Kotlin compiler uses several nullability annotations to determine whether the platform type is nullable or not. See for more information Nullability annotations.

For example, suppose we have the Java class Person

class Person {
    private String name;
    
    public String getName() {
        return name;
    }
}

with the Kotlin data class PersonDto

data class PersonDto(val name: String)

We can write a mapper in a regular manner

class PersonMapper : ObjectMappie<Person, PersonDto>()

Mappie will infer that Person has the source property name and maps it to the target property name of PersonDto.

Do note that Java classes often haven public no-arg constructors, and as such, a mapping can always be constructed without any explicit mappings.