/* * Copyright (C) 2013 The Project Lombok Authors. * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ package lombok.experimental; import static java.lang.annotation.ElementType.*; import static java.lang.annotation.RetentionPolicy.*; import java.lang.annotation.Retention; import java.lang.annotation.Target; /** * The builder annotation creates a so-called 'builder' aspect to the class that is annotated or the class * that contains a member which is annotated with {@code @Builder}. * <p> * If a member is annotated, it must be either a constructor or a static method. If a class is annotated, * then a private constructor is generated with all fields as arguments * (as if {@code @AllArgsConstructor(AccessLevel.PRIVATE)} is present * on the class), and it is as if this constructor has been annotated with {@code @Builder} instead. * <p> * The effect of {@code @Builder} is that an inner class is generated named <code><strong>T</strong>Builder</code>, * with a private constructor. Instances of <code><strong>T</strong>Builder</code> are made with the static * method named {@code builder()} which is also generated for you in the class itself (not in the builder class). * <p> * The <code><strong>T</strong>Builder</code> class contains 1 method for each parameter of the annotated * constructor / static method (each field, when annotating a class), which returns the builder itself. * The builder also has a <code>build()</code> 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 static method that was annotated with {@code @Builder}. The return type of this method will be the same * as the relevant class, unless a static method has been annotated, in which case it'll be equal to the * return type of that method. * <p> * Complete documentation is found at <a href="http://projectlombok.org/features/experimental/Builder.html">the project lombok features page for @Builder</a>. * <p> * <p> * Before: * * <pre> * @Builder * class Example { * private int foo; * private final String bar; * } * </pre> * * After: * * <pre> * 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); * } * } * } * </pre> */ @Target({TYPE, METHOD, CONSTRUCTOR}) @Retention(SOURCE) public @interface Builder { /** Name of the static method that creates a new builder instance. Default: {@code builder}. */ String builderMethodName() default "builder"; /** Name of the instance 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 static methods: {@code (ReturnTypeName)Builder}. */ String builderClassName() default ""; }