Optional of() method in Java with examples

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

// 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

// 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-

Optional of() method in Java with examples

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