如果我们将 Optional.of 方法设为私有，并且只允许 Java 中的 Optional.ofNullable 会怎样； 除了向后兼容会不会有什么问题？

Question

This question has to be updated because it is marked as duplicated, but all the linked questions are not completely matching what is tried to be asked:

Is there a reason, that Optional.of(aNullableVar) is required, as Optional.ofNullable(aNullableVar) checks for null pointer inner the method?

As what Savior answered , a purpose may be like a guard clause:

Object object = getObject();
Optional.of(object);
System.out.println(object.toString());

It's equivalent to:

Object object = getObject();
Objects.requireNonNull(object);
System.out.println(object.toString());

and

Object object = getObject();
if (object == null) {
    throw new NullPointerException();
}
System.out.println(object.toString());

---

Optional.of in Java 8:

public static <T> Optional<T> of(T value) {
    return new Optional<>(value);
}

Optional.ofNullable in Java 8:

public static <T> Optional<T> ofNullable(T value) {
    return value == null ? empty() : of(value);
}

Answer 1

Optional.of serves a double purpose of constructing an Optional with the given non- null value, but also failing fast if the value is actually null .

It's analogous to doing

Objects.requireNonNull(value);
// and then using value

So nothing would really break, you'd just find out much later that you used a null value to create that Optional when you shouldn't have.