Package groovy.transform.builder
Annotation Type Builder
The
@Builder AST transformation is used to help write classes that can be created using fluent api calls.
The transform supports multiple building strategies to cover a range of cases and there are a number
of configuration options to customize the building process.
In addition, a number of annotation attributes let you customise the building process. Not all annotation attributes
are supported by all strategies. See the individual strategy documentation for more details.
If you're an AST hacker, you can also define your own strategy class.
The following strategies are bundled with Groovy:
SimpleStrategyfor creating chained settersExternalStrategywhere you annotate an explicit builder class while leaving some buildee class being built untouchedDefaultStrategywhich creates a nested helper class for instance creationInitializerStrategywhich creates a nested helper class for instance creation which when used with@CompileStaticallows type-safe object creation
new Person(firstName: "Robert", lastName: "Lewandowski", age: 21)or the with statement:
new Person().with {
firstName = "Robert"
lastName = "Lewandowski"
age = 21
}
so you might not find value in using the builder transform at all. But if you need Java integration or in some cases improved type safety, the @Builder transform might prove very useful.-
Optional Element Summary
Optional ElementsModifier and TypeOptional ElementDescriptionbooleanWhether the generated builder should support all properties, including those with names that are considered internal.booleanWhether to include all properties (as per the JavaBean spec) in the generated builder.For strategies which create a builder helper class, the class name to use for the helper class.The method name to use for a builder factory method in the source class for easy access of the builder helper class for strategies which create such a helper class.Class<? extends BuilderASTTransformation.BuilderStrategy>A class capturing the builder strategyFor strategies which create a builder helper class that creates the instance, the method name to call to create the instance.String[]List of field and/or property names to exclude from generated builder methods.booleanWhether to always include helper constructors.A class for which builder methods should be created.String[]List of field and/or property names to include within the generated builder methods.booleanGenerate builder methods for properties from super classes.The prefix to use when creating the setter methods.booleanBy default, properties are set directly using their respective field.
-
Element Details
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forClass
Class forClassA class for which builder methods should be created. It will be an error to leave this attribute with its default value for some strategies.- Default:
- groovy.transform.Undefined.CLASS.class
-
builderStrategy
Class<? extends BuilderASTTransformation.BuilderStrategy> builderStrategyA class capturing the builder strategy- Default:
- groovy.transform.builder.DefaultStrategy.class
-
prefix
String prefixThe prefix to use when creating the setter methods. Default is determined by the strategy which might use "" or "set" but you can choose your own, e.g. "with". If non-empty the first letter of the property will be capitalized before being appended to the prefix.- Default:
- "<DummyUndefinedMarkerString-DoNotUse>"
-
builderClassName
String builderClassNameFor strategies which create a builder helper class, the class name to use for the helper class. Not used if usingforClasssince in such cases the builder class is explicitly supplied. Default is determined by the strategy, e.g. TargetClass + "Builder" or TargetClass + "Initializer".- Default:
- "<DummyUndefinedMarkerString-DoNotUse>"
-
buildMethodName
String buildMethodNameFor strategies which create a builder helper class that creates the instance, the method name to call to create the instance. Default is determined by the strategy, e.g. build or create.- Default:
- "<DummyUndefinedMarkerString-DoNotUse>"
-
builderMethodName
String builderMethodNameThe method name to use for a builder factory method in the source class for easy access of the builder helper class for strategies which create such a helper class. Must not be used if usingforClass. Default is determined by the strategy, e.g. builder or createInitializer.- Default:
- "<DummyUndefinedMarkerString-DoNotUse>"
-
excludes
String[] excludesList of field and/or property names to exclude from generated builder methods. Must not be used if 'includes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values.- Default:
- {}
-
includes
String[] includesList of field and/or property names to include within the generated builder methods. Must not be used if 'excludes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values. The default value is a special marker value indicating that no includes are defined; all fields are included if includes remains undefined and excludes is explicitly or implicitly an empty list.- Default:
- {"<DummyUndefinedMarkerString-DoNotUse>"}
-
useSetters
boolean useSettersBy default, properties are set directly using their respective field. By settinguseSetters=truethen a writable property will be set using its setter. If turning on this flag we recommend that setters that might be called are made null-safe wrt the parameter.- Since:
- 2.5.0
- Default:
- false
-
includeSuperProperties
boolean includeSuperPropertiesGenerate builder methods for properties from super classes.- Since:
- 2.5.0
- Default:
- false
-
allNames
boolean allNamesWhether the generated builder should support all properties, including those with names that are considered internal.- Since:
- 2.5.0
- Default:
- false
-
allProperties
boolean allPropertiesWhether to include all properties (as per the JavaBean spec) in the generated builder. Groovy recognizes any field-like definitions with no explicit visibility as property definitions and always includes them in the@Buildergenerated classes. Groovy also treats any explicitly created getXxx() or isYyy() methods as property getters as per the JavaBean specification. Old versions of Groovy did not. So set this flag to false for the old behavior or if you want to explicitly exclude such properties. Currently only supported by DefaultStrategy and ExternalStrategy.- Since:
- 2.5.0
- Default:
- true
-
force
boolean forceWhether to always include helper constructors. Currently only supported by InitializerStrategy. By default, the InitializerStrategy only adds a needed helper tuple constructor if no@TupleConstructorannotations are present. If such annotations are present, it is assumed they will provide the helper constructor that this strategy needs. If made true, the helper constructor will be generated and it is up to you to make sure this doesn't conflict with any other generated constructors.- Since:
- 2.5.0
- Default:
- false
-