Java 8 | IntToDoubleFunction Interface in Java with Examples

The IntToDoubleFunction Interface is a part of the java.util.function package which has been introduced since Java 8, to implement functional programming in Java. It represents a function which takes in an int-valued argument and gives a double-valued result.

The lambda expression assigned to an object of IntToDoubleFunction type is used to define its applyAsDouble() which eventually applies the given operation on its only argument. It is similar to using an object of type Function<Integer, Double> .

The IntToDoubleFunction interface has only one function:

applyAsDouble() : This method accepts an int-valued argument and gives a double-valued result.

Syntax:

double applyAsDouble(int value)

Parameters: This method takes in one parameter value which is the int-valued argument

Returns: This method returns a double-valued result.

Below is the code to illustrate applyAsDouble() method:

Program

// Java Program to demonstrate
// IntToDoubleFunction's applyAsDouble() method

import java.util.function.IntToDoubleFunction;

public class Main {
    public static void main(String args[])
    {

        // Declare IntToDoubleFunction
        IntToDoubleFunction func = a -> 3.12 * a;

        // Apply the function to get the result as double
        // using applyAsDouble()
        System.out.println(func.applyAsDouble(2));
    }
}

Output:

6.24

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