Java Long doubleValue() Method

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The Long.doubleValue() method in Java is used to convert a Long object to a double primitive.

Table of Contents

1. Introduction
2. doubleValue() Method Syntax
3. Examples
   • Converting a Long to double
   • Performing Arithmetic Operations
   • Handling null Values
4. Real-World Use Case
5. Conclusion

Introduction

The Long.doubleValue() method is an instance method in the Long class in Java. It converts a Long object to a double primitive. This method is useful when you need to perform operations that require double precision on Long objects.

doubleValue()() Method Syntax

The syntax for the Long.doubleValue() method is as follows:

public double doubleValue()

The method returns:

• The double value represented by this Long object.

Examples

Converting a Long to double

The doubleValue() method can be used to convert a Long object to a double primitive.

Example

public class LongToDoubleExample {
    public static void main(String[] args) {
        Long longObject = 123456789L;
        double doubleValue = longObject.doubleValue();

        System.out.println("Double value of 123456789L: " + doubleValue);
    }
}

Output:

Double value of 123456789L: 1.23456789E8

In this example, the Long object 123456789L is converted to the double primitive 1.23456789E8.

Performing Arithmetic Operations

You can use the doubleValue() method to extract the double primitive from a Long object and perform arithmetic operations.

Example

public class ArithmeticOperationsExample {
    public static void main(String[] args) {
        Long longObject1 = 500L;
        Long longObject2 = 200L;

        double sum = longObject1.doubleValue() + longObject2.doubleValue();
        double difference = longObject1.doubleValue() - longObject2.doubleValue();
        double product = longObject1.doubleValue() * longObject2.doubleValue();
        double quotient = longObject1.doubleValue() / longObject2.doubleValue();

        System.out.println("Sum: " + sum);
        System.out.println("Difference: " + difference);
        System.out.println("Product: " + product);
        System.out.println("Quotient: " + quotient);
    }
}

Output:

Sum: 700.0
Difference: 300.0
Product: 100000.0
Quotient: 2.5

In this example, the Long objects 500L and 200L are converted to double primitives, and arithmetic operations are performed on them.

Handling null Values

When dealing with Long objects, it's important to handle null values to avoid NullPointerException.

Example

public class NullHandlingExample {
    public static void main(String[] args) {
        Long longObject = null;

        if (longObject != null) {
            double doubleValue = longObject.doubleValue();
            System.out.println("Double value: " + doubleValue);
        } else {
            System.out.println("The Long object is null.");
        }
    }
}

Output:

The Long object is null.

In this example, the code checks if the Long object is null before attempting to convert it to a double primitive.

Real-World Use Case

Converting User Input

In a real-world application, you might need to convert user input, which is often in the form of Long objects, to double primitives for calculations that require higher precision.

Example

import java.util.Scanner;

public class UserInputExample {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a long number: ");

        Long longObject = scanner.nextLong();
        double doubleValue = longObject.doubleValue();

        double result = doubleValue * 1.5;
        System.out.println("The result of multiplying the input by 1.5 is: " + result);

        scanner.close();
    }
}

Output (example input 123456789):

Enter a long number:
The result of multiplying the input by 1.5 is: 1.851851835E8

In this example, the user input is read as a Long object and then converted to a double primitive for a calculation.

Conclusion

The Long.doubleValue() method in Java is a straightforward way to convert Long objects to double primitives. By understanding how to use this method, you can efficiently handle tasks that involve converting Long objects to double primitives in your Java applications. Whether you are performing arithmetic operations, handling user input, or avoiding null values, the doubleValue() method provides a reliable solution for these tasks.