* If a member is annotated, it must be either a constructor or a method. If a class is annotated, * then a private constructor is generated with all fields as arguments * (as if {@code @AllArgsConstructor(access = AccessLevel.PRIVATE)} is present * on the class), and it is as if this constructor has been annotated with {@code @Builder} instead. * Note that this constructor is only generated if you haven't written any constructors and also haven't * added any explicit {@code @XArgsConstructor} annotations. In those cases, lombok will assume an all-args * constructor is present and generate code that uses it; this means you'd get a compiler error if this * constructor is not present. *
* The effect of {@code @Builder} is that an inner class is generated named TBuilder,
* with a private constructor. Instances of TBuilder are made with the
* method named {@code builder()} which is also generated for you in the class itself (not in the builder class).
*
* The TBuilder class contains 1 method for each parameter of the annotated
* constructor / method (each field, when annotating a class), which returns the builder itself.
* The builder also has a build() method which returns a completed instance of the original type,
* created by passing all parameters as set via the various other methods in the builder to the constructor
* or method that was annotated with {@code @Builder}. The return type of this method will be the same
* as the relevant class, unless a method has been annotated, in which case it'll be equal to the
* return type of that method.
*
* Complete documentation is found at the project lombok features page for @Builder.
*
*
* Before: * *
* @Builder
* class Example<T> {
* private T foo;
* private final String bar;
* }
*
*
* After:
*
*
* class Example<T> {
* private T foo;
* private final String bar;
*
* private Example(T foo, String bar) {
* this.foo = foo;
* this.bar = bar;
* }
*
* public static <T> ExampleBuilder<T> builder() {
* return new ExampleBuilder<T>();
* }
*
* public static class ExampleBuilder<T> {
* private T foo;
* private String bar;
*
* private ExampleBuilder() {}
*
* public ExampleBuilder foo(T foo) {
* this.foo = foo;
* return this;
* }
*
* public ExampleBuilder bar(String bar) {
* this.bar = bar;
* return this;
* }
*
* @java.lang.Override public String toString() {
* return "ExampleBuilder(foo = " + foo + ", bar = " + bar + ")";
* }
*
* public Example build() {
* return new Example(foo, bar);
* }
* }
* }
*
*
* @see Singular
*/
@Target({TYPE, METHOD, CONSTRUCTOR})
@Retention(SOURCE)
public @interface Builder {
/**
* The field annotated with {@code @Default} must have an initializing expression; that expression is taken as the default to be used if not explicitly set during building.
*/
@Target(FIELD)
@Retention(SOURCE)
public @interface Default {}
/** @return Name of the method that creates a new builder instance. Default: {@code builder}. */
String builderMethodName() default "builder";
/** @return Name of the method in the builder class that creates an instance of your {@code @Builder}-annotated class. */
String buildMethodName() default "build";
/**
* Name of the builder class.
*
* Default for {@code @Builder} on types and constructors: {@code (TypeName)Builder}.
* * Default for {@code @Builder} on methods: {@code (ReturnTypeName)Builder}. * * @return Name of the builder class that will be generated (or if it already exists, will be filled with builder elements). */ String builderClassName() default ""; /** * If true, generate an instance method to obtain a builder that is initialized with the values of this instance. * Legal only if {@code @Builder} is used on a constructor, on the type itself, or on a static method that returns * an instance of the declaring type. * * @return Whether to generate a {@code toBuilder()} method. */ boolean toBuilder() default false; /** * Put on a field (in case of {@code @Builder} on a type) or a parameter (for {@code @Builder} on a constructor or static method) to * indicate how lombok should obtain a value for this field or parameter given an instance; this is only relevant if {@code toBuilder} is {@code true}. * * You do not need to supply an {@code @ObtainVia} annotation unless you wish to change the default behaviour: Use a field with the same name. *
* Note that one of {@code field} or {@code method} should be set, or an error is generated. *
* The default behaviour is to obtain a value by referencing the name of the parameter as a field on 'this'. */ @Target({FIELD, PARAMETER}) @Retention(SOURCE) public @interface ObtainVia { /** * @return Tells lombok to obtain a value with the expression {@code this.value}. */ String field() default ""; /** * @return Tells lombok to obtain a value with the expression {@code this.method()}. */ String method() default ""; /** * @return Tells lombok to obtain a value with the expression {@code SelfType.method(this)}; requires {@code method} to be set. */ boolean isStatic() default false; } }