@Accessors

Since

@Accessors was introduced as experimental feature in lombok v0.11.0.

Experimental

Experimental because:

  • We may want to roll these features into a more complete property support concept.
  • New feature - community feedback requested.
Current status: positive - Currently we feel this feature may move out of experimental status with no or minor changes soon.

Overview

The @Accessors annotation is used to configure how lombok generates and looks for getters and setters.

By default, lombok follows the bean specification for getters and setters: The getter for a field named pepper is getPepper for example. However, some might like to break with the bean specification in order to end up with nicer looking APIs. @Accessors lets you do this.

Some programmers like to use a prefix for their fields, i.e. they write fPepper instead of pepper. We strongly discourage doing this, as you can't unit test the validity of your prefixes, and refactor scripts may turn fields into local variables or method names. Furthermore, your tools (such as your editor) can take care of rendering the identifier in a certain way if you want this information to be instantly visible. Nevertheless, you can list the prefixes that your project uses via @Accessors as well.

@Accessors therefore has 3 options:

  • fluent - A boolean. If true, the getter for pepper is just pepper(), and the setter is pepper(T newValue). Furthermore, unless specified, chain defaults to true.
    Default: false.
  • chain - A boolean. If true, generated setters return this instead of void.
    Default: false, unless fluent=true, then Default: true.
  • prefix - A list of strings. If present, fields must be prefixed with any of these prefixes. Each field name is compared to each prefix in the list in turn, and if a match is found, the prefix is stripped out to create the base name for the field. It is legal to include an empty string in the list, which will always match. For characters which are letters, the character following the prefix must not be a lowercase letter, i.e. pepper is not a match even to prefix p, but pEpper would be (and would mean the base name of this field is epper).
  • The @Accessors annotation is legal on types and fields; the annotation that applies is the one on the field if present, otherwise the one on the class. When a @Accessors annotation on a field is present, any @Accessors annotation also present on that field's type is ignored.

With Lombok

01 import lombok.experimental.Accessors;
02 import lombok.Getter;
03 import lombok.Setter;
04 
05 @Accessors(fluent = true)
06 public class AccessorsExample {
07   @Getter @Setter
08   private int age = 10;
09 }
10 
11 class PrefixExample {
12   @Accessors(prefix = "f"@Getter
13   private String fName = "Hello, World!";
14 }

Vanilla Java

01 public class AccessorsExample {
02   private int age = 10;
03   
04   public int age() {
05     return this.age;
06   }
07   
08   public AccessorsExample age(final int age) {
09     this.age = age;
10     return this;
11   }
12 }
13 
14 class PrefixExample {
15   private String fName = "Hello, World!";
16   
17   public String getName() {
18     return this.fName;
19   }
20 }

Supported configuration keys:

lombok.accessors.chain = [true | false] (default: false)
If set to true, any class that either doesn't have an @Accessors annotation, or it does, but that annotation does not have an explicit value for the chain parameter, will act as if @Accessors(chain = true) is present.
lombok.accessors.fluent = [true | false] (default: false)
If set to true, any class that either doesn't have an @Accessors annotation, or it does, but that annotation does not have an explicit value for the fluent parameter, will act as if @Accessors(fluent = true) is present.
lombok.accessors.prefix += a field prefix (default: empty list)
This is a list property; entries can be added with the += operator. Inherited prefixes from parent config files can be removed with the -= operator. Any class that either doesn't have an @Accessors annotation, or it does, but that annotation does not have an explicit value for the prefix parameter, will act as if @Accessors(prefix = {prefixes listed in configuration}) is present.
lombok.accessors.flagUsage = [warning | error] (default: not set)
Lombok will flag any usage of @Accessors as a warning or error if configured.

Small print

The nearest @Accessors annotation is also used for the various methods in lombok that look for getters, such as @EqualsAndHashCode.

If a prefix list is provided and a field does not start with one of them, that field is skipped entirely by lombok, and a warning will be generated.