The of() method of java.util.Optional class in Java is used to get an instance of this Optional class with the specified value of the specified type.
Syntax:
public static <T> Optional<T> of(T value)
Parameters: This method accepts value as parameter of type T to create an Optional instance with this value.
Return value: This method returns an instance of this Optional class with the specified value of the specified type.
Exception: This method throws NullPointerException if the specified value is null.
Below programs illustrate of() method:
Program 1:
// Java program to demonstrate// Optional.of() method import java.util.*; public class GFG { public static void main(String[] args) { // create a Optional Optional<Integer> op = Optional.of(9455); // print value System.out.println("Optional: " + op); }} |
Output:
Optional: Optional[9455]
Program 2:
// Java program to demonstrate// Optional.of() method import java.util.*; public class GFG { public static void main(String[] args) { try { // create a Optional Optional<Integer> op = Optional.of(null); // print value System.out.println("Optional: " + op); } catch (Exception e) { System.out.println(e); } }} |
Output:
java.lang.NullPointerException
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Optional.html#of-T-
