@Value

Immutable classes made very easy.

Since

+ @Value was introduced as experimental feature in lombok v0.11.4. +

+ @Value no longer implies @Wither since lombok v0.11.8. +

+ @Value promoted to the main lombok package since lombok v0.11.10. +

Overview

+ @Value is the immutable variant of @Data; all fields are made private and final by default, and setters are not generated. The class itself is also made final by default, because immutability is not something that can be forced onto a subclass. Like @Data, useful toString(), equals() and hashCode() methods are also generated, each field gets a getter method, and a constructor that covers every + argument (except final fields that are initialized in the field declaration) is also generated. +

+ In practice, @Value is shorthand for: final @ToString @EqualsAndHashCode @AllArgsConstructor @FieldDefaults(makeFinal = true, level = AccessLevel.PRIVATE) @Getter. +

+ It is possible to override the final-by-default and private-by-default behaviour using either an explicit access level on a field, or by using the @NonFinal or @PackagePrivate annotations.
+ It is possible to override any default behaviour for any of the 'parts' that make up @Value by explicitly using that annotation. +

With Lombok

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Vanilla Java

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Small print

+ Look for the documentation on the 'parts' of @Value: @ToString, @EqualsAndHashCode, @AllArgsConstructor, @FieldDefaults, and @Getter. +

+ For classes with generics, it's useful to have a static method which serves as a constructor, because inference of generic parameters via static methods works in java6 and avoids having to use the diamond operator. While you can force this by applying an explicit @AllArgsConstructor(staticConstructor="of") annotation, there's also the @Value(staticConstructor="of") feature, which will make the generated all-arguments constructor private, and generates a public static method named of which is a wrapper around this private constructor. +

+ @Value was an experimental feature from v0.11.4 to v0.11.9 (as @lombok.experimental.Value). It has since been moved into the core package. The old annotation is still + around (and is an alias). It will eventually be removed in a future version, though. +

@Builder

It's like drinking tea with an extended pinky while wearing a monocle: No-hassle fancy-pants APIs for object creation!

... and Bob's your uncle: No-hassle fancy-pants APIs for object creation!

Since

@@ -24,7 +24,6 @@ Experimental because:

New feature - community feedback requested.
This feature will move to the core package soon.

Current status: sure thing - This feature will move to the core package soon.

@@ -43,7 +42,7 @@

An inner static class named FooBuilder, with the same type arguments as the static method (called the builder).

In the builder: One private non-static non-final field for each parameter of the target.

In the builder: A package private no-args empty constructor.

In the builder: A 'setter'-like method for each parmeter of the target: It has the same type as that parameter and the same name. +

In the builder: A 'setter'-like method for each parameter of the target: It has the same type as that parameter and the same name. It returns the builder itself, so that the setter calls can be chained, as in the above example.

In the builder: A build() method which calls the static method, passing in each field. It returns the same type that the target returns.

@@ -52,18 +51,16 @@ Each listed generated element will be silently skipped if that element already exists (disregarding parameter counts and looking only at names). This includes the builder itself: If that class already exists, lombok will simply start injecting fields and methods inside this already existing - class, unless of course the fields / methods to be injected already exist. + class, unless of course the fields / methods to be injected already exist. You may not put any other method (or constructor) generating lombok annotation + on a builder class though; for example, you can not put @EqualsAndHashCode on the builder class.

Now that the "static method" mode is clear, putting a @Builder annotation on a constructor functions similarly; effectively, constructors are just static methods that have a special syntax to invoke them: Their 'return type' is the class they construct, and their type parameters are the same as the type parameters of the class itself.

- Finally, applying @Builder to a class is as if you added @AllArgsConstructor(acces = AccessLevel.PACKAGE) to the class and applied the - @Builder annotation to this all-args-constructor. Note that this constructor is only generated if there is no explicit - constructor present in the so annotated class, but this @AllArgsConstructor has priority over any other implicitly - generated lombok constructor (such as @Data and @Value). If an explicit constructor is present, no constructor is generated, - but the builder will be created with the assumption that this constructor exists. If you've written another constructor, you'll get a compilation error.
- The solution is to either let lombok write this constructor (delete your own), or, annotate your constructor instead. + Finally, applying @Builder to a class is as if you added @AllArgsConstructor(access = AccessLevel.PACKAGE) to the class and applied the + @Builder annotation to this all-args-constructor. This only works if you haven't written any explicit constructors yourself. If you do have an + explicit constructor, put the @Builder annotation on the constructor instead of on the class.

The name of the builder class is FoobarBuilder, where Foobar is the simplified, title-cased form of the return type of the target - that is, the name of your type for @Builder on constructors and types, and the name of the return type for @Builder @@ -71,9 +68,15 @@ FancyListBuilder<T>. If @Builder is applied to a static method that returns void, the builder will be named VoidBuilder.

- The only configurable aspect of builder are the builder's class name (default: return type + 'Builder'), the build() method's name, and the - builder() method's name:
- @Builder(builderClassName = "HelloWorldBuilder", buildMethodName = "execute", builderMethodName = "helloWorld") + The configurable aspects of builder are:

The builder's class name (default: return type + 'Builder')
The build() method's name (default: "build")
The builder() method's name (default: "builder")
The 'fluent' nature of the generated 'setter'-like methods. A fluent 'setter' is named just fieldName(), a non-fluent one is named setFieldName(). (default: true)
The 'chain' nature of the generated 'setter'-like methods. A chainable 'setter' returns the builder object itself, letting you chain 'set' calls. A non-chainable setter returns void. (default: true)

+ Example usage where all options are changed from their defaults:
+

@Builder(builderClassName = "HelloWorldBuilder", buildMethodName = "execute", builderMethodName = "helloWorld", fluent = false, chain = false)