Groovy 2.2.1

groovy.transform
[Java] Annotation Type ToString

java.lang.Object
  groovy.transform.ToString

@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
 }
 println new AgedThing(name:'Lassie', age:5)
 
Then the output will be:
 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
 }
 println new NamedThing(name: null)
 
Which results in:
 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)
 
Authors:
Paul King
Andre Steingress
See Also:
Immutable
Canonical
Since:
1.8.0


 
Optional Element Summary
boolean cache

Whether to cache toString() calculations.

java.lang.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 generated toString.

boolean includeNames

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

java.lang.String includes

List of field and/or property names to include within the generated toString.

 
Method Summary
 
Methods inherited from class Object
wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll
 

Element Detail

cache

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). @default false
Since:
2.1.0


excludes

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 {}


ignoreNulls

public boolean ignoreNulls
Don't display any fields or properties with value null. @default false


includeFields

public boolean includeFields
Include fields as well as properties in generated toString. @default false


includeNames

public boolean includeNames
Whether to include names of properties/fields in generated toString. @default false


includePackage

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. @default true
Since:
2.0.6


includeSuper

public boolean includeSuper
Whether to include super in generated toString. @default false


includes

public String[] includes
List of field and/or property names to include within the generated toString. 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. @default {}


 

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