How to have Java method return generic list of any type?

casting, generics, java, list, reflection

Solution

private Object actuallyT;

public <T> List<T> magicalListGetter(Class<T> klazz) {
    List<T> list = new ArrayList<>();
    list.add(klazz.cast(actuallyT));
    try {
        list.add(klazz.getConstructor().newInstance()); // If default constructor
    } ...
    return list;
}

One can give a generic type parameter to a method too. You have correctly deduced that one needs the correct class instance, to create things (`klazz.getConstructor().newInstance()`).

Problem

I would like to write a method that would return a `java.util.List` of any type without the need to typecast anything: ``` List<User> users = magicalListGetter(User.class); List<Vehicle> vehicles = magicalListGetter(Vehicle.class); List<String> strings = magicalListGetter(String.class); ``` What would the method signature look like? Something like this, perhaps(?): ``` public List<<?> ?> magicalListGetter(Class<?> clazz) { List<?> list = doMagicalVooDooHere(); return list; } ```

Original source