Package eu.mihosoft.vmf.core

Annotation Type Annotation

@Retention(RUNTIME)
@Target({METHOD,TYPE})
@Repeatable(Annotations.class)
public @interface Annotation

An annotation can be used to add custom metadata to entities and properties of a model.

Example Model:

 package mypkg.vmfmodel;
 
 import eu.mihosoft.vmf.core.*;
 
 interface Node {
 
     String getId();
 
     @Annotation(key="api",value="input")
     Node getA();
 
     @Annotation(key="api",value="input")
     Node getB();
 
     @Annotation(key="api",value="output")
     Node getC();
 
 }

Retrieving Annotations:

We can retrieve property annotations with the following API call:

 Property p = ...
 List annotations = p.annotations();
 

Filter Annotations:

Using the stream API, one can query a specific annotation (e.g. filtered by key). Here's an example that prints all properties of a node instance annotated as input (key="api", value="input").

 // predicate to filter inputs
 Predicate isInput = (p) -> {
     return p.annotationByKey("api").
         map(ann->"input".equals(ann.getValue())).orElse(false);
 };
 
 // query inputs:
 n.vmf().reflect().properties().stream().filter(isInput).forEach(p->{
     System.out.println(
         "-> input  param '" + p.getName() + "' -> node: " + ((Node)p.get()).getId()
     );
 });
 

Created by miho on 05.12.2018.

See Also:

Tutorial on Annotation Support

Required Element Summary

Required Elements

Modifier and Type	Required Element	Description
java.lang.String	value	Value of the annotation.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element	Description
java.lang.String	key	Key of the annotation, e.g., "api" or "model".

Element Detail

value

java.lang.String value

Value of the annotation. This can be an arbitrary string. Consumers of the annotation are responsible for parsing the value string.

key

java.lang.String key

Key of the annotation, e.g., "api" or "model".

Default:

""