Template method return type not matching returned instances

It does need a cast as you have declared the result.

The method signature you have defined says that the caller, not the body of createPanel, gets to decide what V is, and the function must give it that kind of V, regardless of everything else. That's not what you have, so the cast is unsafe.

There is not, in fact, a way in Java's type system that the result type of a function is "some type that extends both JPanel and LabeledInput."

The most viable alternative is to define your own abstract class that extends JPanel and LabeledInput and then make ItemSelectComboPanel and ItemSelectRadioPanel both extend that class.