Loading a Class from a String

Question

I want to instantiate a class by the value of a String. I found several tutorials that show several methods for doing this. The class MUST inherit from a certain interface

Answer 1

No, there is no better way (by design). You are not supposed to do this, Java is designed as a type-safe language. However, I can understand that you sometimes need to do things like this, and for that purposes you can create a library function like this:

public  T instantiate(final String className, final Class type){
    try{
        return type.cast(Class.forName(className).newInstance());
    } catch(InstantiationException
          | IllegalAccessException
          | ClassNotFoundException e){
        throw new IllegalStateException(e);
    }
}

Now your client code can at least call this method without casting:

MyInterface thingy =
    instantiate("com.foo.bar.MyInterfaceImpl", MyInterface.class);