heyimMarc
11/22/2017 - 2:57 PM
@Value Immutable classes made very easy.
@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, except that explicitly including an implementation of any of the relevant methods simply means that part won't be generated and no warning will be emitted. For example, if you write your own toString, no error occurs, and lombok will not generate a toString. Also, any explicit constructor, no matter the arguments list, implies lombok will not generate a constructor. If you do want lombok to generate the all-args constructor, add @AllArgsConstructor to the class. You can mark any constructor or method with @lombok.experimental.Tolerate to hide them from lombok.
It is possible to override the final-by-default and private-by-default behavior using either an explicit access level on a field, or by using the @NonFinal or @PackagePrivate annotations. It is possible to override any default behavior for any of the 'parts' that make up @Value by explicitly using that annotation.
import lombok.AccessLevel;
import lombok.experimental.NonFinal;
import lombok.experimental.Value;
import lombok.experimental.Wither;
import lombok.ToString;
@Value public class ValueExample {
String name;
@Wither(AccessLevel.PACKAGE) @NonFinal int age;
double score;
protected String[] tags;
@ToString(includeFieldNames=true)
@Value(staticConstructor="of")
public static class Exercise<T> {
String name;
T value;
}
}