Java 8 Optional. Why of and ofNullable?

Question

I have a question regarding Java 8\'s Optional, the purpose of which is to tackle NullPointerException exceptions.

The question is, what is the reason for h

Answer 1

Code example: Optional.of() VS Optional.ofNullable()

@Test
public void TestOptional() {

    String message = "Hello World!";
    System.out.println("message -> " + message + "\n");

    Optional genderOptional = Optional.of(message);
    System.out.println("Optional.of(message) -> " + genderOptional);
    System.out.println("Optional.of(message).get() -> " + genderOptional.get());
    try {
        Optional.of(null);
    } catch (java.lang.NullPointerException e) {
        System.out.println("Optional.of(null) -> java.lang.NullPointerException \n");
    }

    System.out.println("Optional.empty() -> " + Optional.empty() + "\n");

    System.out.println("Optional.ofNullable(null) -> " + Optional.ofNullable(null));
    System.out.println("Optional.ofNullable(message) -> " + Optional.ofNullable(message));
    System.out.println("Optional.ofNullable(message).get() -> " + Optional.ofNullable(message).get());

}

Output:

message -> Hello World!

Optional.of(message) -> Optional[Hello World!]
Optional.of(message).get() -> Hello World!
Optional.of(null) -> java.lang.NullPointerException 

Optional.empty() -> Optional.empty

Optional.ofNullable(null) -> Optional.empty
Optional.ofNullable(message) -> Optional[Hello World!]
Optional.ofNullable(message).get() -> Hello World!