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.
- Authors:
- Paul King
- See Also:
- Immutable
- Canonical
- Since:
- 1.8.0
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