How do I use the DoubleBinaryOperator functional interface in Java?

By Wayan in Util Package 0 Comment

The DoubleBinaryOperator interface in Java is part of java.util.function and is used to represent an operation that takes two double-valued operands and produces a double-valued result. It is a functional interface, meaning it has a single abstract method that can be implemented using a lambda expression or method reference.

The single abstract method in DoubleBinaryOperator is:

double applyAsDouble(double left, double right);

How to Use DoubleBinaryOperator

1. Using a Lambda Expression

A common way to use DoubleBinaryOperator is to define the operation using a lambda expression.

Example:

package org.kodejava.util.function;

import java.util.function.DoubleBinaryOperator;

public class DoubleBinaryOperatorExample {
    public static void main(String[] args) {
        // Define a DoubleBinaryOperator to add two double values
        DoubleBinaryOperator addition = (a, b) -> a + b;

        // Apply the operator on some values
        double result = addition.applyAsDouble(5.5, 4.5);

        // Output: Addition Result: 10.0
        System.out.println("Addition Result: " + result);
    }
}

2. Using a Method Reference

If we have a method that matches the signature of the applyAsDouble method, we can use a method reference to implement the DoubleBinaryOperator.

Example:

package org.kodejava.util.function;

import java.util.function.DoubleBinaryOperator;

public class DoubleBinaryOperatorExample2 {

    // Define a static method for multiplication
    public static double multiply(double a, double b) {
        return a * b;
    }

    public static void main(String[] args) {
        // Use a method reference to implement DoubleBinaryOperator
        DoubleBinaryOperator multiplication = DoubleBinaryOperatorExample2::multiply;

        // Apply the operator on some values
        double result = multiplication.applyAsDouble(3.5, 2.0);

        // Output: Multiplication Result: 7.0
        System.out.println("Multiplication Result: " + result);
    }
}

3. Using with Other Functional Interfaces

We can combine DoubleBinaryOperator with other functional interfaces or use it in streams for processing numerical data.

Example with parallel reduction:

package org.kodejava.util.function;

import java.util.Arrays;
import java.util.function.DoubleBinaryOperator;

public class DoubleBinaryOperatorExample3 {
    public static void main(String[] args) {
        // Define a DoubleBinaryOperator for subtraction
        DoubleBinaryOperator subtraction = (a, b) -> a - b;

        // Use it in a reduction with doubles in a stream
        double[] numbers = {10.0, 3.0, 4.0};
        double result = Arrays.stream(numbers).reduce(0.0, subtraction);

        // Output: Reduction Result: -17.0
        System.out.println("Reduction Result: " + result);
    }
}

Key Points

  1. Functional Interface: It is annotated with @FunctionalInterface, so you can use lambda expressions or method references for implementation.
  2. Purpose: Useful when working with operations involving two double operands and a double result, such as addition, subtraction, multiplication, division, or any custom operation.
  3. Stream Operations: Can be effectively utilized in stream reductions or parallel processing involving numerical computations.

By leveraging DoubleBinaryOperator, we can write concise and reusable numerical operations in your Java programs.

Wayan
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