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-
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