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:
@CompileStatic
allows type-safe object creationnew 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.
Type | Name and Description |
---|---|
String |
buildMethodName For strategies which create a builder helper class that creates the instance, the method name to call to create the instance. |
String |
builderClassName For strategies which create a builder helper class, the class name to use for the helper class. |
String |
builderMethodName 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 BuilderStrategy> |
builderStrategy A class capturing the builder strategy @default DefaultStrategy.class |
String[] |
excludes List of field and/or property names to exclude from generated builder methods. |
Class |
forClass A class for which builder methods should be created. |
String[] |
includes List of field and/or property names to include within the generated builder methods. |
String |
prefix The prefix to use when creating the setter methods. |
For 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 Undefined.STRING
For strategies which create a builder helper class, the class name to use for the helper class.
Not used if using forClass
since in such cases the builder class is explicitly supplied.
Default is determined by the strategy, e.g. TargetClass + "Builder" or TargetClass + "Initializer".
@default Undefined.STRING
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.
Must not be used if using forClass
.
Default is determined by the strategy, e.g. builder or createInitializer.
@default Undefined.STRING
A class capturing the builder strategy @default DefaultStrategy.class
List 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 {}
A 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 .CLASS.class
List 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. @default {}
The 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 Undefined.STRING