Java JUnit array of classes for SuiteClasses syntax

Question

Currently I have the following code to test my class...

@RunWith(Suite.class)
@SuiteClasses( { MyClass.class, MyNewClass } )
public class AllTests {
    public static void suite() {        
    }
}

What I'd like to do would be the following, but it's syntactically incorrect - what would be the correct format?...

 Class<?>[] classArray = new Class<?>[] {
        MyClass.class, MyNewClass.class
  };

 @RunWith(Suite.class)
    @SuiteClasses( classArray  )
    public class AllTests {
        public static void suite() {        
        }
    }

try removing the Generic <?>

chrislhardin
– chrislhardin

2012-11-14 14:51:00 +00:00
Commented Nov 14, 2012 at 14:51 — chrislhardin
– chrislhardin, Commented Nov 14, 2012 at 14:51

artbristol · Accepted Answer · 2012-11-14 14:51:22Z

4

Unfortunately you can't. Annotations need to take compile-time constants, so you have to use { MyClass.class, MyNewClass.class }.

answered Nov 14, 2012 at 14:51

artbristol

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1 Comment

pholser Over a year ago

This is the correct answer. It's about what you feed to an annotation, not how you've declared the array variable.

Edwin Buck · Accepted Answer · 2012-11-14 15:12:42Z

--- Update ---

The problem seems to stem from Annotations. Annotations require compile time constants, which means you cannot "build an array" of classes in a manner that might have you reassigning the array, or modifying it before the annotated method could access it.

Credit to artbristol for pointing out the obvious. Initially I started down the wrong path, which was to attempt to find out why your array did compile in my 1.7 environment.

Actually, the compile time constant restriction on Annotations makes perfect sense when considering that Annotations are meant to extends java programming via declarative means.

--- Original Post ---

Instead of attempting a wildcard, use

 Class<Object>[] classArray = new Class<Object>[] { .... };

It semi-defeats the purpose of generics, since everything extends from Object; but, it will satisfy the "shove anything into it" requirements you need.

Community · Accepted Answer · 2017-05-23 12:18:43Z

1

By K.Sierra from "SCJP study guide": "Keep in mind that the wildcards can be used only for reference declarations (including arguments, variables, return types, and so on). They can't be used as the type parameter when you create a new typed collection. Think about that—while a reference can be abstract and polymorphic, the actual object created must be of a specific type."

List<?> foo = new ArrayList<? extends Animal>();

Problem: you cannot use wildcard notation in the object creation. So the new ArrayList() will not compile.

EDIT: @artbristol pointed another problem which is compile-time constant passed to the annotation. Look at the responses in this thread, they might be helpful. One of them suggests ENUM as a workaround. How to use an array constant in an annotation

edited May 23, 2017 at 12:18

CommunityBot

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answered Nov 14, 2012 at 14:53

BartoszMiller

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