Java DoubleSupplier

Introduction

In Java, the DoubleSupplier interface is a functional interface that represents a supplier of double-valued results. It is part of the java.util.function package and is used to generate or supply a double value without any input.

Table of Contents

1. What is DoubleSupplier?
2. Methods and Syntax
3. Examples of DoubleSupplier
4. Real-World Use Case
5. Conclusion

1. What is DoubleSupplier?

DoubleSupplier is a functional interface that provides a double result when called. It is commonly used in scenarios where a constant or calculated double value needs to be supplied on demand.

2. Methods and Syntax

The main method in the DoubleSupplier interface is:

• double getAsDouble(): Gets a double result.

Syntax

DoubleSupplier doubleSupplier = () -> {
    // logic to return a double value
    return result;
};

3. Examples of DoubleSupplier

Example 1: Returning a Constant Value

import java.util.function.DoubleSupplier;

public class ConstantDoubleSupplier {
    public static void main(String[] args) {
        // Define a DoubleSupplier that returns a constant value
        DoubleSupplier constantValue = () -> 3.14;

        double result = constantValue.getAsDouble();

        System.out.println("Constant Value: " + result);
    }
}

Output:

Constant Value: 3.14

Example 2: Generating a Random Double

import java.util.function.DoubleSupplier;

public class RandomDoubleSupplier {
    public static void main(String[] args) {
        // Define a DoubleSupplier that returns a random double
        DoubleSupplier randomValue = () -> Math.random();

        double result = randomValue.getAsDouble();

        System.out.println("Random Value: " + result);
    }
}

Output:

Random Value: [Random number between 0.0 and 1.0]

4. Real-World Use Case: Supplying Temperature Data

In monitoring systems, DoubleSupplier can be used to supply temperature readings from a sensor.

import java.util.function.DoubleSupplier;

public class TemperatureSensor {
    public static void main(String[] args) {
        // Define a DoubleSupplier to simulate temperature readings
        DoubleSupplier temperatureReading = () -> getTemperature();

        double temperature = temperatureReading.getAsDouble();

        System.out.println("Current Temperature: " + temperature);
    }

    // Simulated method to get temperature
    private static double getTemperature() {
        // Logic to retrieve temperature data, e.g., from a sensor
        return 25.0; // Assume a constant temperature for this example
    }
}

Output:

Current Temperature: 25.0

Conclusion

The DoubleSupplier interface is used in Java for providing double values without any input parameters. It is particularly beneficial in scenarios like generating constant values, random numbers, or sensor data. Using DoubleSupplier can help create modular and reusable code, especially in functional programming contexts.