Package groovy.transform

# Annotation Interface ToString

@Documented @Retention(SOURCE) @Target(TYPE) public @interface ToString
Class annotation used to assist in the creation of `toString()` methods in classes. The `@ToString` annotation instructs the compiler to execute an AST transformation which adds the necessary toString() method.

It allows you to write classes in this shortened form:

     @ToString
     class Customer {
         String first, last
         int age
         Date since = new Date()
         Collection favItems
         private answer = 42
     }
     println new Customer(first:'Tom', last:'Jones', age:21, favItems:['Books', 'Games'])

Which will have this output:

     Customer(Tom, Jones, 21, Wed Jul 14 23:57:14 EST 2010, [Books, Games])

There are numerous options to customize the format of the generated output. E.g. if you change the first annotation to:

     @ToString(includeNames=true)

Then the output will be:

     Customer(first:Tom, last:Jones, age:21, since:Wed Jul 14 23:57:50 EST 2010, favItems:[Books, Games])

Or if you change the first annotation to:

     @ToString(includeNames=true,includeFields=true,excludes="since,favItems")

Then the output will be:

     Customer(first:Tom, last:Jones, age:21, answer:42)

If you have this example:

     import groovy.transform.ToString
     @ToString class NamedThing {
         String name
     }
     @ToString(includeNames=true,includeSuper=true)
     class AgedThing extends NamedThing {
         int age
     }
     String agedThingAsString = new AgedThing(name:'Lassie', age:5).toString()
     assert agedThingAsString == 'AgedThing(age:5, super:NamedThing(Lassie))'

`@ToString` can also be used in conjunction with `@Canonical` and `@Immutable`.

If you want to omit fields or properties referring to `null`, you can use the `ignoreNulls` flag:

     import groovy.transform.ToString
     @ToString(ignoreNulls = true) class NamedThing {
         String name
     }
     assert new NamedThing(name: null).toString() == 'NamedThing()'

By default the fully-qualified class name is used as part of the generated toString. If you want to exclude the package, you can set the includePackage flag to false, e.g.:

     package my.company
     import groovy.transform.ToString
     @ToString(includePackage = false) class NamedThing {
         String name
     }
     println new NamedThing(name: "Lassie")

Which results in:

     NamedThing(name: Lassie)

If the includePackage flag is `true` (the default), then the output will be:

     my.company.NamedThing(name: Lassie)

More examples:

     //--------------------------------------------------------------------------
     // Most simple implementation of toString.
     import groovy.transform.ToString

     @ToString
     class Person {
         String name
         List likes
         private boolean active = false
     }

     def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

     assert person.toString() == 'Person(mrhaki, [Groovy, Java])'

     //--------------------------------------------------------------------------
     // includeNames to output the names of the properties.
     import groovy.transform.ToString

     @ToString(includeNames=true)
     class Person {
         String name
         List likes
         private boolean active = false
     }

     def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

     assert person.toString() == 'Person(name:mrhaki, likes:[Groovy, Java])'

     //--------------------------------------------------------------------------
     // includeFields to not only output properties, but also field values.
     import groovy.transform.ToString

     @ToString(includeNames=true, includeFields=true)
     class Person {
         String name
         List likes
         private boolean active = false
     }

     def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

     assert person.toString() == 'Person(name:mrhaki, likes:[Groovy, Java], active:false)'

     //--------------------------------------------------------------------------
     // Use includeSuper to include properties from super class in output.
     import groovy.transform.ToString

     @ToString(includeNames=true)
     class Person {
         String name
         List likes
         private boolean active = false
     }

     @ToString(includeSuper=true, includeNames=true)
     class Student extends Person {
         List courses
     }

     def student = new Student(name: 'mrhaki', likes: ['Groovy', 'Java'], courses: ['IT', 'Business'])

     assert student.toString() == 'Student(courses:[IT, Business], super:Person(name:mrhaki, likes:[Groovy, Java]))'

     //--------------------------------------------------------------------------
     // excludes active field and likes property from output
     import groovy.transform.ToString

     @ToString(includeNames=true, includeFields=true, excludes='active,likes')
     class Person {
         String name
         List likes
         private boolean active = false
     }

     def person = new Person(name: 'mrhaki', likes: ['Groovy', 'Java'])

     assert person.toString() == 'Person(name:mrhaki)'

     //--------------------------------------------------------------------------
     // Don't include the package name in the output
     package com.mrhaki.blog.groovy

     import groovy.transform.*

     @ToString(includePackage=false)
     class Course {
         String title
         Integer maxAttendees
     }

     final Course course = new Course(title: 'Groovy 101', maxAttendees: 200)

     assert course.toString() == 'Course(Groovy 101, 200)'

     //--------------------------------------------------------------------------
     // Don't use properties with null value.
     package com.mrhaki.blog.groovy

     import groovy.transform.*

     @ToString(ignoreNulls=true)
     class Course {
         String title
         Integer maxAttendees
     }

     final Course course = new Course(title: 'Groovy 101')

     assert course.toString() == 'com.mrhaki.blog.groovy.Course(Groovy 101)'

     //--------------------------------------------------------------------------
     // Cache toString() result.
     package com.mrhaki.blog.groovy

     import groovy.transform.*

     @ToString(cache=true)
     class Course {
         String title
         Integer maxAttendees
     }

     Course course = new Course(title: 'Groovy 101', maxAttendees: 200)

     assert course.toString() == 'com.mrhaki.blog.groovy.Course(Groovy 101, 200)'

     // Value change will not be reflected in toString().
     course.title = 'Grails with REST'

     assert course.toString() == 'com.mrhaki.blog.groovy.Course(Groovy 101, 200)'
     assert course.title == 'Grails with REST'

Since:
  1.8.0
See Also:
  - `Immutable`
  - `Canonical`

- ## Optional Element Summary

  Optional Elements
  Modifier and Type
  Optional Element
  Description
  `boolean`
  `allNames`
  Whether to include all fields and/or properties in the generated toString, including those with names that are considered internal.
  `boolean`
  `allProperties`
  Whether to include all properties (as per the JavaBean spec) in the generated toString.
  `boolean`
  `cache`
  Whether to cache toString() calculations.
  `String[]`
  `excludes`
  List of field and/or property names to exclude from generated toString.
  `String`
  `fieldSeparator`
  The string to use between each property/field.
  `boolean`
  `ignoreNulls`
  Don't display any fields or properties with value `null`.
  `boolean`
  `includeFields`
  Include fields as well as properties in the generated toString.
  `boolean`
  `includeNames`
  Whether to include names of properties/fields in the generated toString.
  `boolean`
  `includePackage`
  Whether to include the fully-qualified class name (i.e.
  `String[]`
  `includes`
  List of field and/or property names to include within the generated toString.
  `boolean`
  `includeSuper`
  Whether to include the toString() of super in the generated toString.
  `boolean`
  `includeSuperFields`
  Include super fields in the generated toString.
  `boolean`
  `includeSuperProperties`
  Whether to include super properties in the generated toString.
  `String`
  `leftDelimiter`
  The String to use after the classname and before the list of properties/fields.
  `String`
  `nameValueSeparator`
  The string to use between the name of the property/field and its value when `includeNames` is true.
  `boolean`
  `pojo`
  Whether to avoid using Groovy runtime methods when printing the toString for class members.
  `String`
  `rightDelimiter`
  The String to use after the list of properties/fields.
  `boolean`
  `useGetters`
  Whether to access properties directly by their fields (faster) or via their getters.

- ## Element Details

  - ### excludes

    String[] excludes
    List of field and/or property names to exclude from generated toString. Must not be used if 'includes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values.
    Default:
      {}

  - ### includes

    String[] includes
    List of field and/or property names to include within the generated toString. The order of inclusion is determined by the order in which the names are specified. Must not be used if 'excludes' is used. For convenience, a String with comma separated names can be used in addition to an array (using Groovy's literal list notation) of String values. The default value is a special marker value indicating that no includes are defined; all fields and/or properties are included if 'includes' remains undefined and 'excludes' is explicitly or implicitly an empty list. The special name 'super' can be used instead of using the 'includeSuper' flag.
    Default:
      {"<DummyUndefinedMarkerString-DoNotUse>"}

  - ### includeSuper

    boolean includeSuper
    Whether to include the toString() of super in the generated toString.
    Default:
      false

  - ### includeNames

    boolean includeNames
    Whether to include names of properties/fields in the generated toString.
    Default:
      false

  - ### includeFields

    boolean includeFields
    Include fields as well as properties in the generated toString. Fields come after any properties.
    Default:
      false

  - ### includeSuperProperties

    boolean includeSuperProperties
    Whether to include super properties in the generated toString. Groovy properties, JavaBean properties and fields (in that order) from superclasses come after the members from a subclass (unless 'includes' is used to determine the order).
    Since:
      2.4.0
    Default:
      false

  - ### includeSuperFields

    boolean includeSuperFields
    Include super fields in the generated toString. Groovy properties, JavaBean properties and fields (in that order) from superclasses come after the members from a subclass (unless 'includes' is used to determine the order).
    Since:
      2.5.0
    Default:
      false

  - ### ignoreNulls

    boolean ignoreNulls
    Don't display any fields or properties with value `null`.
    Default:
      false

  - ### includePackage

    boolean includePackage
    Whether to include the fully-qualified class name (i.e. including the package) or just the simple class name in the generated toString.
    Since:
      2.0.6
    Default:
      true

  - ### allProperties

    boolean allProperties
    Whether to include all properties (as per the JavaBean spec) in the generated toString. Groovy recognizes any field-like definitions with no explicit visibility as property definitions and always includes them in the `@ToString` generated toString (as well as auto-generating the appropriate getters and setters). Groovy also treats any explicitly created getXxx() or isYyy() methods as property getters as per the JavaBean specification. Old versions of Groovy did not. So set this flag to false for the old behavior or if you want to explicitly exclude such properties. JavaBean properties come after any Groovy properties but before any fields for a given class (unless 'includes' is used to determine the order).
    Since:
      2.5.0
    Default:
      true

  - ### cache

    boolean cache
    Whether to cache toString() calculations. You should only set this to true if you know the object is immutable (or technically mutable but never changed).
    Since:
      2.1.0
    Default:
      false

  - ### allNames

    boolean allNames
    Whether to include all fields and/or properties in the generated toString, including those with names that are considered internal.
    Since:
      2.5.0
    Default:
      false

  - ### pojo

    boolean pojo
    Whether to avoid using Groovy runtime methods when printing the toString for class members. The generated code is more similar to what is typically used in POJO classes. The presence of the `@POJO` annotation on a class is looked for by default but this annotation attribute allows the feature to be explicitly configured if desired. NOTE: this is an incubating feature and may change in future versions.
    Since:
      4.0.0
    Default:
      false

  - ### leftDelimiter

    String leftDelimiter
    The String to use after the classname and before the list of properties/fields.
    Since:
      4.0.0
    Default:
      "("

  - ### rightDelimiter

    String rightDelimiter
    The String to use after the list of properties/fields.
    Since:
      4.0.0
    Default:
      ")"

  - ### nameValueSeparator

    String nameValueSeparator
    The string to use between the name of the property/field and its value when `includeNames` is true.
    Since:
      4.0.0
    Default:
      ":"

  - ### fieldSeparator

    String fieldSeparator
    The string to use between each property/field.
    Since:
      4.0.0
    Default:
      ", "

  - ### useGetters

    boolean useGetters
    Whether to access properties directly by their fields (faster) or via their getters.
    Since:
      4.0.12
    Default:
      true