OptionalLong ifPresent(LongConsumer) method in Java with examples

The ifPresent(java.util.function.LongConsumer) method helps us to perform the specified LongConsumer action the value of this OptionalLong object. If a value is not present in this OptionalLong, then this method does nothing. 

Syntax:

public void ifPresent(LongConsumer action)

Parameters: This method accepts a parameter action which is the action to be performed on this Optional, if a value is present. 

Return value: This method returns nothing. 

Exception: This method throw NullPointerException if a value is present and the given action is null. 

Below programs illustrate ifPresent(LongConsumer) method: 

Program 1:

Java

// Java program to demonstrate
// OptionalLong.ifPresent(LongConsumer) method

import java.util.OptionalLong;

public class GFG {

    public static void main(String[] args)
    {

        // create a OptionalLong
        OptionalLong oplong
            = OptionalLong.of(23456745678L);

        // apply ifPresent(LongConsumer)
        oplong.ifPresent((value) -> {

            value = Math.round(value * 0.19);
            System.out.println("Value after modification:=> "
                               + value);
        });
    }
}

Output: Program 2:

Java

// Java program to demonstrate
// OptionalLong.ifPresent(LongConsumer) method

import java.util.OptionalLong;

public class GFG {

    public static void main(String[] args)
    {

        // create a OptionalLong
        OptionalLong oplong = OptionalLong.empty();

        // apply ifPresent(LongConsumer)
        oplong.ifPresent((value) -> {

            value = value * 132435;
            System.out.println("Value:=> "
                               + value);
        });

        System.out.println("As OptionalLong is empty value"
                           + " is not modified");
    }
}

Output: References: https://docs.oracle.com/javase/10/docs/api/java/util/OptionalLong.html#ifPresent(java.util.function.LongConsumer)