Java Double longValue() Method

The Double.longValue() method in Java is used to convert a Double object to a long primitive.

Table of Contents

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

Introduction

The Double.longValue() method is an instance method in the Double class in Java. It converts a Double object to a long primitive. This method is useful when you need to narrow down a Double to a long for certain operations or storage, bearing in mind that this conversion may lead to loss of precision.

longValue()() Method Syntax

The syntax for the Double.longValue() method is as follows:

public long longValue()

The method returns:

• The long value represented by this Double object.

Examples

Converting a Double to long

The longValue() method can be used to convert a Double object to a long primitive.

Example

public class DoubleToLongExample {
    public static void main(String[] args) {
        Double doubleObject = 123.45;
        long longValue = doubleObject.longValue();

        System.out.println("Long value of 123.45: " + longValue);
    }
}

Output:

Long value of 123.45: 123

In this example, the Double object 123.45 is converted to the long primitive 123.

Performing Arithmetic Operations

You can use the longValue() method to extract the long primitive from a Double object and perform arithmetic operations.

Example

public class ArithmeticOperationsExample {
    public static void main(String[] args) {
        Double doubleObject1 = 50.75;
        Double doubleObject2 = 25.25;

        long sum = doubleObject1.longValue() + doubleObject2.longValue();
        long difference = doubleObject1.longValue() - doubleObject2.longValue();
        long product = doubleObject1.longValue() * doubleObject2.longValue();
        long quotient = doubleObject1.longValue() / doubleObject2.longValue();

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

Output:

Sum: 75
Difference: 25
Product: 1200
Quotient: 2

In this example, the Double objects 50.75 and 25.25 are converted to long primitives, and arithmetic operations are performed on them.

Handling null Values

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

Example

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

        if (doubleObject != null) {
            long longValue = doubleObject.longValue();
            System.out.println("Long value: " + longValue);
        } else {
            System.out.println("The Double object is null.");
        }
    }
}

Output:

The Double object is null.

In this example, the code checks if the Double object is null before attempting to convert it to a long 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 Double objects, to long primitives for calculations.

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 number: ");

        Double doubleObject = scanner.nextDouble();
        long longValue = doubleObject.longValue();

        long result = longValue * 2;
        System.out.println("The result of doubling the input is: " + result);

        scanner.close();
    }
}

Output (example input 12.34):

Enter a number:
The result of doubling the input is: 24

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

Conclusion

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