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Optional of() method in Java with examples

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  • Last Updated : 30 Jul, 2019
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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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