Java: check an attribute value exists or not in list by annotation

Question

As the title, I want to check an attribute value is exists or not in a list by annotation. Ex:

private final String[] list = {"a", "b", "c", "d"}
@Includes(list = list)
private String state;

but there is an error Attribute must be constant How can I do it ? Btw, is it a good solution to check this by annotation ? Here is my annotation:

@Target(ElementType.FIELD)
@Inherited
@Retention(RetentionPolicy.RUNTIME)
public @interface Includes {
    String[] list();
}

score 1 · Accepted Answer · answered Oct 27 '17 at 08:10

1

The error says it clearly:

The value for annotation attribute Includes.list must be an array initializer

With non-array variables, the value must be final and static, however, there is no way to do this with arrays. It means you have to do this workaround:

@Includes(list = {"a", "b", "c", "d"})
private String state;

Moreover, your array initialization is wrong, use {} instead of [].

answered Oct 27 '17 at 08:10

Nikolas Charalambidis

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Is it a good practice to use annotation to check it include in array ? – Thach Huynh Oct 27 '17 at 08:39
You haven't specified why do you want to check if the array contains a certain value, so I can't give you an answer. Is it because of validations, or do you want to practise annotations on a simple example? – Nikolas Charalambidis Oct 27 '17 at 09:17
I am practicing on a simple example – Thach Huynh Oct 27 '17 at 09:41

Java: check an attribute value exists or not in list by annotation

1 Answers1