.class == getClass() test fails

Question

Here's a small code I wrote to check the (is it called reflection API? not sure) classes at runtime, however I am not getting the intended results. Here is the code:

public class Outer {
    public Outer(){
        System.out.println("Outer Class");
    }
    public class Inner {
        public Inner(){         
            System.out.println("Inner Class");
        }
    }
}

Also here is the main function that I wrote to run the code and test it...

public class ClassTest {

    public static void main(String[] args) {

        Outer outObj = new Outer();
        Outer.Inner inObj = outObj.new Inner();

        // Using Reflection
        Class objTyp = inObj.getClass();
        System.out.println(objTyp.getName());

        //Testing Reflection
        if(objTyp.getClass() == Outer.Inner.class){
            System.out.println("Match classes!");
        }else{
            System.out.println("Mismatch classes!");
        }
    }
}

The test fails with the following error:

if(objTyp.getClass() == Outer.Inner.class){ ^ where CAP#1 is a fresh type-variable: CAP#1 extends Class from capture of ? extends Class 1 error

Please help me to correct the code. What am I missing? Thanks.

You should compare `Outer.Inner.class` with `objType`, not `objType.getClass()`. — Arnaud Denoyelle, Aug 13 '13 at 11:05
@boxed__l `Outer.Inner.class` is a class literal so == should work. — Arnaud Denoyelle, Aug 13 '13 at 11:05
@ArnaudDenoyelle agreed ...getName() returns a String literal — boxed__l, Aug 13 '13 at 11:11

score 7 · Accepted Answer · answered Aug 13 '13 at 11:07

You are comparing Outer.Inner.class with objTyp.getClass() instead of objTyp.

objTyp is of type Class<Outer.Inner>.
objTyp.getClass() is of type Class<Class<Outer.Inner>>.
Outer.Inner.class is a class literal of type Class<Outer.Inner>.

Hence, objTyp.getClass() has no chance to equal Outer.Inner.class.

    Outer outObj = new Outer();
    Outer.Inner inObj = outObj.new Inner();

    // Using Reflection
    Class objTyp = inObj.getClass();
    System.out.println(objTyp.getName());

    //  >>>>> objTyp is already inObj.getClass() <<<<<<
    if(objTyp.getClass() == Outer.Inner.class){
        System.out.println("Match classes!");
    }else{
        System.out.println("Mismatch classes!");
    }

So doesn't `Class>` return the `Object` base class and test should fail printing `Mismatch classes!`? — Anurupa_Dey, Aug 13 '13 at 11:13
It does not compile because you can't use == on objects of different types (`Class>>` vs `Class>`). You would have the same error trying to compare `List` vs `List`. — Arnaud Denoyelle, Aug 13 '13 at 11:17

.class == getClass() test fails

1 Answers1