![]() In your case, a parameter annotion should be way the compiler will enforce the specified usage restriction. I also suggest you indicate the program element to which the annotation type At is applicable. In your case, you want to make it available for reading reflectively so you need it must use RetentionPolicy.RUNTIME to record the annotation in the class file but stil be retained by VM at run time. The annotation MatricParam is used to retrieve the parameter value from the URI and assign it to a method parameter. When you get the annotation of that class, you are getting the annotation of String rather than of the method parameter itself, and String has no annotations ( view source ). A call to MethodgetParameterTypes () returns an array of the parameters' types, meaning their classes. Java annotations were added to Java from Java 5. An annotation application in Scala looks like a constructor invocation, for instantiating a Java annotation one has to use named arguments: Scala 2 and 3. This is not a flaw in the implementation. Being meta data, Java annotations do not directly affect the execution of your code, although some types of annotations can actually be used for that purpose. ![]() In this article, we will discuss how to change annotation value at runtime using Reflection. These annotations can be processed at compile time and embedded to class files or can be retained and accessed at runtime using Reflection. To change how long annotations are retained, you may use the Retention meta-annotation. Jakob Jenkov Last update: Java annotations are used to provide meta data for your Java code. Annotations are decorators that are applied to Java constructs, such as classes, methods, or fields, that associate metadata with the construct. Annotations, a form of metadata which you can add to Java code. ![]() By default, annotations are recorded in the class file by the compiler but need not be retained by the VM at run time (RetentionPolicy.CLASS retention policy is being applied). ![]()
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