#6 Wildcard generics problem

[Marcin Sokolowski]

Following code is not compiling:

public class SomeTest
{
public static interface A
{
public Class<?> get();
}

@Test
public void testSomething()
{
A mock = EasyMock createMock(A.class);

EasyMock.expect(mock.get()).andReturn(String.class);
replay(mock);

}
}

Error message is as follows:

The method andReturn(Class<capture#2-of ?="">) in the type
IExpectationSetters<Class<capture#2-of ?="">> is not applicable for the arguments
(Class<String>)

To make it valid I need to change Class<?> to raw type Class. Then it works.

Obviously following code is perfectly valid:

public class StringA implements A
{
public Class<?> get() { return String.class; }
}

[Henri Tremblay]

Logged In: YES
user_id=893525
Originator: NO

You are facing a special generic feature called type erasure. You can't set a wildcard to a fix type. For instance you can't do

Class<String> c = a.get();

There's no way that I know for EasyMock to workaround this. To have something more flexible, you can type like this:

public <T> Class<T> get();

Typed like this you could have done this:

expect(mock.<String>get()).andReturn(String.class);

In your case, the only solution is

expect((Class) mock.get()).andReturn(String.class);

You'll get a compilation warning but that's the best you can do.

[SourceForge Robot]

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