Double longValue() in Java with Examples

Java is a powerful object-oriented language that allows for a high degree of control and precision over a wide range of data types. One such functionality is the double long Value(), a key method used to convert a long value to a double. This article provides a comprehensive understanding of the Double long Value() method in Java, including its syntax, explanation, and different approaches to using it.

Syntax

The syntax for the Double long Value() method is quite straightforward −

public double doubleValue()

Explanation of Syntax

The method doubleValue() is an instance method, belonging to the Number class and overridden in Double class. It converts a Double object into a primitive double. This method does not take any parameters and returns the double value of this Double object.

Code of the Syntax

Double num = new Double(123.45);
double d = num.doubleValue();
System.out.println(d);

In the code above, the Double object num is instantiated with a value of 123.45. The doubleValue() method is then called to convert num into a primitive double.

Algorithm

• Initialize the Double object.

• Call the doubleValue() method on the object.

• The doubleValue() method returns the double value of the object.

Approaches

Let's examine two different approaches to using attributes in Java Servlets.

Approach 1: Basic Conversion

In its simplest form, the doubleValue() method is used to convert a Double object to a double primitive.

Example

public class Main {
   public static void main(String[] args) {
      Double num = new Double(789.32);
      double d = num.doubleValue();
      System.out.println(d);
   }
}

Output

789.32

Explanation

This is a simple Java program contained within a class named "Main". Inside the class, there's a single method called "main". The "main" method serves as the entry point for the program.

Inside the "main" method, an object "num" is created using the `Double` class in Java, which is a wrapper class for the primitive data type `double`. The `Double` object is initialized with a value of 789.32.

Then, the `doubleValue()` method is called on the "num" object. This method is a built-in function in Java that transforms a `Double` object into a primitive `double` data type. The output of the `doubleValue()` method is assigned to the `double` variable "d".

Lastly, the value of "d" is printed to the console using the `System.out.println(d);` statement.

Thus, this program illustrates a straightforward application of object creation and conversion from a `Double` object to a `double` primitive data type in Java. It highlights how to utilize the `doubleValue()` method and output the results to the console.

Approach 2: Conversion in Mathematical Operations

The doubleValue() method can be particularly useful when performing mathematical operations that require double precision.

Example

public class Main {
   public static void main(String[] args) {
      Double num1 = new Double(45.67);
      Double num2 = new Double(32.14);
      double result = num1.doubleValue() / num2.doubleValue();
      System.out.println(result);
   }
}

Output

1.4209707529558184

Explanation

This Java program, encapsulated within a class named "Main", employs the doubleValue() method to perform a division operation between two Double objects.

Inside the main method, which serves as the starting point for the program, two Double objects are created, num1 and num2, with respective values of 45.67 and 32.14. The Double class is a wrapper for the primitive double data type in Java, allowing the use of double as if it were a full-fledged object.

Subsequently, the doubleValue() method is invoked on num1 and num2. This method is an inherent part of the Double class in Java and serves to convert a Double object into a primitive double data type. The result of these changes is then utilized in a division activity, the consequence of which is doled out to the twofold factor "result".

At last, the program prints the worth of "result" to the control center utilizing the System.out.println(result); explanation. This specific Java piece, hence, features the use of the doubleValue() strategy in numerical tasks.

Approach 3: Conversion in Arrays

The doubleValue() method can also be used when dealing with arrays of Double objects.

Example

public class Main {
   public static void main(String[] args) {
      Double[] numArray = {new Double(10.1), new Double(20.2), new Double(30.3)};
      double sum = 0;
      for (Double num : numArray) {
         sum += num.doubleValue();
      }
      System.out.println(sum);
   }
}

Output

60.599999999999994

Explanation

This runnable Java program, housed within a class named "Main", demonstrates the application of the doubleValue() method when working with an array of Double objects.

Within the main method, an array of Double objects, numArray, is initialized with three elements − 10.1, 20.2, and 30.3. This array represents a sequence of Double objects. A double variable, sum, is also declared and initialized to 0. It is used to accumulate the total sum of the Double elements in the array.

The program then initiates a for-each loop, iterating through each Double object in numArray. For every iteration, the doubleValue() method is invoked on the Double object. This built-in Java method converts a Double object into a primitive double data type. The double value is then added to sum.

Once all the elements in numArray have been processed, the final value of sum is printed to the console using System.out.println(sum);. This Java code hence illustrates how to use the doubleValue() method when dealing with arrays of Double objects, highlighting its usefulness in aggregation operations such as calculating the sum of elements.

Approach 4: Conversion in Collections

The doubleValue() method can also be used in collections like Lists or Sets of Double objects.

Example

import java.util.Arrays;
import java.util.List;

public class Main {
   public static void main(String[] args) {
      List<Double> numList = Arrays.asList(new Double(1.1), new Double(2.2), new Double(3.3));
      double product = 1;
      for (Double num : numList) {
         product *= num.doubleValue();
      }
      System.out.println(product);
   }
}

Output

7.986000000000001

Explanation

This Java program, encased within a class named "Main", showcases the usage of the doubleValue() method while working with a List of Double objects.

The entry point of the program is the main method. Here, a List of Double objects, numList, is declared and initialized with three elements: 1.1, 2.2, and 3.3. A double variable, product, is also declared and initialized to 1. This variable will store the running product of the elements in the List.

The program then executes a for-each loop, traversing through each Double object in numList. During each iteration, the doubleValue() method is invoked on the current Double object. This method, built into the Double class in Java, transforms a Double object into a primitive double data type. The resulting double value is then multiplied with product, updating its value.

Upon completing the loop, having processed all the elements in numList, the final product is printed to the console via the System.out.println(product); statement. Hence, this program effectively illustrates the use of the doubleValue() method when dealing with collections of Double objects, particularly for cumulative multiplication operations.

Conclusion

The double long Value() method in Java provides a simple, efficient way to convert a Double object into a primitive double, proving its usefulness in various scenarios. Whether you're working with basic conversions, mathematical operations, arrays, or collections, the doubleValue() method allows for seamless transformations, enhancing your Java programming experience.