Java annotations question

[lukiasz]

Hello,

I'm trying to make insertions to a lot of different fields in database using jax-ws created implementation based on given wsdl. Here is sample of generated class I'm expecting at input of one of methods:

public class InputType1{

    @XmlElement(name = "FIELD_DB_1", required = true)
    protected NewType fielddb1;

    @XmlElement(name = "FIELD_DB_2", required = true)
    protected String fielddb2;
}

Everything is working properly, but I have to type fields name every time I want to store it in DB. DB fields names are shown in XmlElement annotations and they're coming from wsdl, so I thought it would be nice to reconstruct them at run-time:

Class cls = InputType1.class;
for (java.lang.reflect.Field field : cls.getDeclaredFields()) {
	Class fieldCls = field.getClass();
	Annotation[] annotations = fieldCls.getAnnotations();
	for(Annotation annotation : annotations){
		if(annotation instanceof javax.xml.bind.annotation.XmlElement){
			XmlElement myAnnotation = (XmlElement) annotation;
			System.out.println("name: " + myAnnotation.name());
		}
	}

Unfortunately, 'annotations' table is empty. I read somewhere, that it is necessary to have second annotation, namely @Retention(RetentionPolicy.RUNTIME) which tells that annotation should be persisted during run-time. So, I tried to add it into my generated class, so it looks like:

public class InputType1{
    @Retention(RetentionPolicy.RUNTIME)
    @XmlElement(name = "FIELD_DB_1", required = true)
    protected NewType fielddb1;

    @Retention(RetentionPolicy.RUNTIME)
    @XmlElement(name = "FIELD_DB_2", required = true)
    protected String fielddb2;
}

but Eclipse is telling me that this annotation is disallowed for this location. What should I do?

Best regards!

Lukasz

[Potato]

you should add

@Retention(RetentionPolicy.RUNTIME)

right above your XmlElement annotation

so like:

@Retention(RetentionPolicy.RUNTIME)
@interface XmlElement {
String name();
boolean required() default false;

// ...

}

that way, any XmlElement annotations are actually retained by the VM and you can read them.

[lukiasz]

Thanks for your response,

I've solved it right now. An XmlElement is definied in javax.xml.bind.annotation namespace, so I suppose I can't change it. Fortunately, when I put mouse cursor over it, Eclipse showed me, that this annotation already has a valid retention value:

@Target(value={FIELD, METHOD, PARAMETER})
@Retention(value=RUNTIME)

Eventually, problem was in reading annotations, I should call:

Annotation[] annotations = field.getAnnotations();

instead of

Class fieldCls = field.getClass();
    Annotation[] annotations = fieldCls.getAnnotations();

Just for sake of curiosity - is there a way to override annotations in existing class or somehow put them without modification existing code?