如何在没有警告的情况下转换java.lang.Class <？>类型的对象？

Question

I've got some code that looks like this:

Class<?> clazz = Class.forName(someClassName);
if(TargetClass.class.isAssignableFrom(clazz))
{
    Class<? extends TargetClass> narrowClass = (Class<? extends TargetClass>)clazz;
    // Use the narrowClass for stuff
}

This code give me an "unchecked cast" warning, probably because the isAssignableFrom check doesn't count as a "check". It's not possible to use instanceof , here, because you can't check the runtime type due to type-erasure.

Is there any way to write this code without a compiler warning? Or is the only way to get rid of the warning to add @SupprssWarnings("unckeched") to the method?

Answer 1

Use the following method:

 Class<? extends TargetClass> narrowClass = clazz.asSubclass(TargetClass.class);

Here is a Link to the documentation.