What is the difference between Objects.requireNonNullElse () and Optional.ofNullable (). OrElse ()?

Question

Java 9 introduces the requireNonNullElse and requireNonNullElseGet into the Objects class. Are they functionally distinct from Optional.ofNullable() orElse() and orElseGet() ?

 String foo = null; Objects.requireNonNullElse(foo, "nonNull");//returns the string "nonNull" Optional.ofNullable(foo).orElse("nonNull");//also returns the string "nonNull" 

If they have no functional difference, why are Objects added?

Answer 1

There is one slight difference in their behavior. Objects.requireNonNullElse() requires one of the parameters to be non-empty, otherwise a NullPointerException is thrown.

 String foo = null, bar = null; Optional.ofNullable(foo).orElse(bar);//returns a null value Objects.requireNonNullElse(foo, bar);//throws a NullPointerException 

Answer 2

The conceptual difference between choosing one over the other is explained in their documentation. He relies on the consumer API approach to choose which one should be used effectively by them.

Optional is a container object that may or may not contain a non-zero value.

A variable whose type is Optional should never be null ; This should always point to an Optional instance.

This is a value based class; the use of identification sensitive operations (including referential equality (==), an identifier hash code, or synchronization) on instances of the Optional may have unpredictable results and should be avoided.

• ofNullable

  returns Optional with the current value if the specified value is not null, otherwise empty Optional

• orElse

  returns a value, if present otherwise, returns another .

The following behavior follows:

 String foo = null; => Optional.ofNullable(foo).orElse("nonNull") => Optional.ofNullable(null).orElse("nonNull") => Optional.empty().orElse("nonNull") => return otherwise "nonNull" 

same as traverses

 String foo = null, bar = null; => Optional.ofNullable(foo).orElse(bar); => Optional.ofNullable(null).orElse(bar); => Optional.empty().orElse(bar) => return otherwise 'bar' => returns null 

---

Objects - a class consisting of static utility methods for working on objects or checking certain conditions before an operation.

These utilities include null or null-tolerant methods for calculating the hash code of an object, returning a string for the object, comparing two objects, and checking whether indexes or sub-ranges are values ​​out of bounds.

• requireNonNullElse

  returns the first argument if it is not zero; otherwise, the second argument if it is not zero

Therefore, the difference in behavior:

 String foo = null; => Objects.requireNonNullElse(foo, "nonNull") => Objects.requireNonNullElse(null, "nonNull"); 

which further evaluates internally if requireNonNull("nonNull", "defaultObj") and then

 => returns "nonNull" since its a non-null value 

now that he crosses

 String foo = null, bar = null; => Objects.requireNonNullElse(foo, bar); => Objects.requireNonNullElse(null, bar); 

It checks internally if requireNonNull(bar, "defaultObj") , which then

 => throws a NullPointerException 

As indicated also

throws NullPointerException - if both obj null and defaultObj null