The hashCode() method of java.util.Optional class in Java is used to get the hashCode value of this Optional instance. If there is no value present in this Optional instance, then this method returns 0.
Syntax:
public int hashCode()
Parameter: This method do not accepts any parameter.
Return Value: This method returns the hashCode value of this Optional instance. If there is no value present in this Optional instance, then this method returns 0.
Exception: This method do not throw any Exception.
Program 1:
// Java program to demonstrate// the above method  import java.util.*;  public class OptionalDemo {    public static void main(String[] args)    {          Optional<Integer> op            = Optional.of(456);          System.out.println("Optional: "                           + op);          System.out.println("Optional hashCode value: "                           + op.hashCode());    }} |
Output:
Optional: Optional[456] Optional hashCode value: 456
Program 2:
// Java program to demonstrate// the above method  import java.util.*;  public class OptionalDemo {    public static void main(String[] args)    {          Optional<Integer> op            = Optional.empty();          System.out.println("Optional: "                           + op);          System.out.println("Optional hashCode value: "                           + op.hashCode());    }} |
Output:
Optional: Optional.empty Optional hashCode value: 0
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Optional.html#hashCode–
