Module jakarta.validation
Package jakarta.validation.valueextraction

Interface ValueExtractor<T>

Type Parameters:
T - the container type handled by a specific implementation
public interface ValueExtractor<T>
Defines the logic used to extract the values from a container object of type T.

A value extractor for a generic type such as Optional, List or Map is tied to one specific type parameter of T. The ExtractedValue annotation is used to mark that type parameter. A value extractor for a non-generic type such as OptionalInt needs to declare the type of the wrapped element(s) using ExtractedValue.type().

The extracted values are passed to the corresponding method of the ValueExtractor.ValueReceiver.

A typical value extractor implementation for List may look like this: 

 public class ListValueExtractor implements
         ValueExtractor<List<@ExtractedValue ?>> {

     @Override
     public void extractValues(List<?> originalValue, ValueReceiver receiver) {
         for ( int i = 0; i < originalValue.size(); i++ ) {
             receiver.indexedValue( "<list element>", i, originalValue.get( i ) );
         }
     }
 }
Since:
2.0
See Also: