java 8 Optional code example

Example 1: check if optional is empty java

@Test
public void givenNull_whenCreatesNullable_thenCorrect() {
    String name = null;
    Optional<String> opt = Optional.ofNullable(name);
    assertFalse(opt.isPresent());
}

Example 2: instantiate optinal java 8

Person p = new Person();
Optional<Person> op = Optional.of(p);

Example 3: java optional to collection

public static <T> List<T> toList(Optional<T> opt) {
    return opt
            .map(Collections::singletonList)
            .orElseGet(Collections::emptyList);
}