【JDK8】 Optional 用法記錄
阿新 • • 發佈:2020-07-30
Optional
of 與 ofNullable 的區別
/** * Returns an {@code Optional} with the specified present non-null value. * * @param <T> the class of the value * @param value the value to be present, which must be non-null * @return an {@code Optional} with the value present * @throws NullPointerException if value is null */ public static <T> Optional<T> of(T value) { return new Optional<>(value); }
/** * Returns an {@code Optional} describing the specified value, if non-null, * otherwise returns an empty {@code Optional}. * * @param <T> the class of the value * @param value the possibly-null value to describe * @return an {@code Optional} with a present value if the specified value * is non-null, otherwise an empty {@code Optional} */ public static <T> Optional<T> ofNullable(T value) { return value == null ? empty() : of(value); }
- of 不允許為null
- ofNullable 允許為null