The isPresent() method of java.util.Optional class in Java is used to find out if there is a value present in this Optional instance. If there is no value present in this Optional instance, then this method returns false, else true.
Syntax:
public boolean isPresent()
Parameters: This method do not accept any parameter.
Return value: This method returns a boolean value stating whether if there is a value present in this Optional instance.
Below programs illustrate isPresent() method:
Program 1:
// Java program to demonstrate// Optional.isPresent() 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); // check for the value System.out.println("Is any value present: " + op.isPresent()); }} |
Output:
Optional: Optional[9455] Is any value present: true
Program 2:
// Java program to demonstrate// Optional.isPresent() method import java.util.*; public class GFG { public static void main(String[] args) { // create a Optional Optional<Integer> op = Optional.empty(); // print value System.out.println("Optional: " + op); try { // check for the value System.out.println("Is any value present: " + op.isPresent()); } catch (Exception e) { System.out.println(e); } }} |
Output:
Optional: Optional.empty Is any value present: false
Reference: https://docs.oracle.com/javase/9/docs/api/java/util/Optional.html#isPresent–
