Reference

This page is a comprehensive reference for all annotations, naming conventions, and validation rules in the Caffeinate annotation processor.

Annotations

Annotation	Target	Description
@Immutable	Interface	Generates immutable implementation with private final fields, all-args constructor, getters
@Mutable	Interface	Generates mutable implementation with private fields, no-args + all-args constructors, getters, setters
@ToString	Interface	Customizes toString() generation (styles: STRING_JOINER, TO_STRING_BUILDER)

Naming conventions

Method-to-property mapping

The processor derives property names and types from the method signatures declared in the annotated interface.

Method pattern	Property name	Type
getFirstName()	firstName	Return type of getter
isActive()	active	boolean
setFirstName(String)	firstName (must match getter)	Parameter type (must match getter return type)

• The get or is prefix is stripped and the remaining name is decapitalized to produce the field name.
• Setter names must follow the set* pattern and the derived field name and parameter type must match an existing getter-derived property.

Generated class naming

The generated class is always named <InterfaceName>Impl and placed in the same package as the source interface. For example, an interface com.example.Person produces com.example.PersonImpl.

Validation rules

The processor reports compilation errors when annotated interfaces contain methods that do not conform to the expected patterns. The tables below list every validation rule along with the exact error message produced.

Both @Immutable and @Mutable

Condition	Error message
Annotation applied to a class or enum (not an interface)	@Immutable can only be applied to interfaces / @Mutable can only be applied to interfaces

@Immutable

These rules are enforced by PropertyDiscoveryStrategy.

Condition	Error message
Method has parameters	Methods in @Immutable interfaces must have no parameters
Method returns void	Methods in @Immutable interfaces must not return void
Method name doesn't start with get or is	Methods in @Immutable interfaces must follow get*/is* naming convention

@Mutable

These rules are enforced by MutablePropertyDiscoveryStrategy.

Condition	Error message
Non-setter method has parameters	Methods in @Mutable interfaces must have no parameters (except setters)
Void method doesn't follow set* convention	Void methods in @Mutable interfaces must follow set* naming convention
Method doesn't follow get*/is*/set* convention	Methods in @Mutable interfaces must follow get*/is*/set* naming convention

@Mutable setter validation

These rules are enforced by SetterValidationStrategy after property discovery. Each declared setter is checked against the getter-derived properties.

Condition	Error message
Setter doesn't match any getter-derived property (by field name and type)	Setter setX does not match any getter-derived property (where setX is the actual setter name)