Java wild card BestPractices for casting

Question

I have researched this extensively and cant seem to find a best practice for this scenario.

ArrayList<GenericObject<?>> list = new ArrayList<>();
list.add( new GenericObject<Integer>(6) ); // Autoboxing
list.add( new GenericObject<String>("HI") );
if(list.get( 0 ).getGenaricValue().getClass() == Integer.class){

        GenericObject<Integer> gi = (GenericObject<Integer>) list.get( 0 );
        System.out.println("Was Integer");
        System.out.println(gi);
    }
}

while this block of code works the cast from GenericObject <?> to GenericObject<Integer> gives an unchecked warning. Now as you can see i have clearly checked the type with my if statement so I am not paranoid about an exception but is there a better way to do this without having to suppress the unchecked warning? Is there a best practice for this scenario? I have read the entire Generics oracle tutorial here and i have read a lot of stackoverflow posts but none that seem to answer this problem. any help would be appreciated thanks.

Answer 1

No, there's no better way than to suppress the warning, with an explanation:

@SuppressWarnings("unchecked") // this is okay because [insert reasoning]
GenericObject<Integer> gi = (GenericObject<Integer>) list.get( 0 );

Note that this isn't necessarily a good design however - it's best to avoid unchecked casts if possible, if only because they can be hard to justify. For example, what if gi had earlier been typed as a GenericObject<Object> or GenericObject<Number> and just happened to hold an Integer? It might be better to check and cast the value itself:

GenericObject<?> go = list.get(0);
Object obj = go.getGenericValue();
if (obj instanceof Integer) { // or obj.getClass() == Integer.class
     System.out.println("Was Integer");
}