Package: groovy.transform

## [Java] Annotation Type ToString

- groovy.transform.ToString

-     @Documented
      @Retention(RetentionPolicy.RUNTIME)
      @Target({ElementType.TYPE})
      @GroovyASTTransformationClass("org.codehaus.groovy.transform.ToStringASTTransformation")
      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'

  See Also:
    Immutable
    Canonical
  Since:
    1.8.0

- - ### Element Summary

    Optional Element Summary
    Type | Name and 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.
    `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. including the package) or just the simple class name in 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[]` | `includes` List of field and/or property names to include within the generated toString.

  - ### Inherited Methods Summary

    Inherited Methods
    Methods inherited from class | Name
    --- | ---
    `class Object` | `wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll`

- - ### Element Detail

    - #### public 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

    - #### public 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

    - #### public 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

    - #### public 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:
        {}

    - #### public boolean ignoreNulls

      Don't display any fields or properties with value `null`.

      Default:
        false

    - #### public boolean includeFields

      Include fields as well as properties in the generated toString. Fields come after any properties.

      Default:
        false

    - #### public boolean includeNames

      Whether to include names of properties/fields in the generated toString.

      Default:
        false

    - #### public 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

    - #### public boolean includeSuper

      Whether to include the toString() of super in the generated toString.

      Default:
        false

    - #### public 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

    - #### public 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

    - #### public 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:
        { Undefined.STRING }