I want to get the value of an annotated parameter used in a method invocation:
public class Launch {
public static void main(String[] args) {
System.out.println("hello");
testAnn(15);
}
private static void testAnn(@IntRange(minValue = 1,maxValue = 10)int babyAge) {
System.out.println("babyAge is :"+babyAge);
}
}
What I'm trying is create a custom annotation to validate an integer value range, the annotation takes min
and max
value, so if anyone calls this function using an integer value outside this range, a message error will occur with some hints about what is going wrong.
I'm working in a Java Annotation Process to get the value and compare it with the included max/min
ones in @IntRange
This is what I got:
@Override
public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
for(TypeElement annotaion: annotations) {
Set<? extends Element> annotatedElements = roundEnv.getElementsAnnotatedWith(IntRange.class);
for (Element element : annotatedElements) {
Executable methodElement= (Executable) element.asType();
ExecutableType methodExcutableType = (ExecutableType) element.asType();
String elementParamClassName = methodElement.getParameterTypes()[0].getCanonicalName();
if(!elementParamClassName.equals(PARAM_TYPE_NAME)) {
messager.printMessage(Diagnostic.Kind.ERROR,"Parameter type should be int not "+elementParamClassName);
}else {
IntRange rangeAnno = element.getAnnotation(IntRange.class);
int maxValue = rangeAnno.maxValue();
int minValue = rangeAnno.minValue();
//code to retrive argument passed to the function with
//annotated parameter (@IntRange(..))
}
}
}
return true;
}
You cannot use a Java Annotation Processing because it works only at compile time , so you will be able to get the provided values of @IntRange
annotation but not the current one of the method parameter. More information here
What you really need is a custom validator and you can find how to do it here
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