What are Java annotations used for?
Annotations are used to provide supplement information about a program. Annotations start with ‘@’. Annotations do not change action of a compiled program. Annotations help to associate metadata (information) to the program elements i.e. instance variables, constructors, methods, classes, etc.
Does the order of Java annotations matter?
In almost all cases the answer is No, the order has no effect. But in fact it is a bit more complicated. When getting the annotation of an element during runtime, you also have access to the order. The docs have more info on how the order is determined.
When do you use an annotation in Java?
Java annotation can be used to define the metadata of a Java class or class element. We can use Java annotation at the compile time to instruct the compiler about the build process. Annotation is also used at runtime to get insight into the properties of class elements. Java annotation can be added to an element in the following way:
How to create a repeatable annotation in Java?
For an annotation to be repeatable it must be annotated with the @Repeatable annotation, which is defined in the java.lang.annotation package. Its value field specifies the container type for the repeatable annotation. The container is specified as an annotation whose value field is an array of the repeatable annotation type.
How are annotations not part of inheritance in Java?
Annotations cannot participate in inheritance. Annotations methods may not have arguments. Annotations cannot be generic or specify a throws clause. Annotations must return: an enum or primitive type or an annotation, String, or Class object.
Why are annotations not included in Javadoc comments?
It is a marker interface that tells a tool that an annotation is to be documented. Annotations are not included by Javadoc comments. Use of @Documented annotation in the code enables tools like Javadoc to process it and include the annotation type information in the generated document.