Question

Write a complete Java application to prompt the user for the double radius of a sphere, and call method sphereVolume to calculate and display the volume of the sphere. Use the following statement to calculate the volume: double volume = ( 4.0 / 3.0 ) * Math.PI * Math.pow( radius, 3 )

Short answer

Import Scanner, prompt for radius, use `sphereVolume` method to compute and print volume.

Step-by-step solution

Import Necessary Packages

First, we need to import the Scanner class from the java.util package to handle user input. Add the line `import java.util.Scanner;` at the beginning of your program.

Define the Class and Main Method

Create a new class for your Java application, and define the main method within it. This is the entry point of the application. Use the syntax: ```java public class SphereVolumeCalculator { public static void main(String[] args) { // Code goes here } } ```

Create a Scanner Object and Prompt for Input

Inside the main method, create a Scanner object to read from the standard input. Prompt the user to enter the radius using ```java Scanner scanner = new Scanner(System.in); System.out.print("Enter the radius of the sphere: "); double radius = scanner.nextDouble(); ```

Define and Call the sphereVolume Method

Define a method named `sphereVolume` that takes a double as a parameter and returns a double value representing the volume. This method uses the formula provided: ```java public static double sphereVolume(double radius) { return (4.0 / 3.0) * Math.PI * Math.pow(radius, 3); } ```

Calculate and Display the Volume

Within the main method, call the `sphereVolume` method using the input radius and print the resulting volume. Add this code: ```java double volume = sphereVolume(radius); System.out.printf("The volume of the sphere is: %.2f ", volume); ```

Handle Input Resource Closure

Close the scanner object to free up resources when input is no longer needed. Add the line `scanner.close();` at the end of the main method.

Key concepts

Java Classes

In Java, everything is organized into classes. Classes serve as blueprints to create objects within an application.
They bundle data and methods that work on the data into a single unit. In our exercise, we need to create a class named `SphereVolumeCalculator`.
This class acts as a container for all the operations related to calculating the volume of a sphere.

• Classes define the structure by housing variables and methods.
• They serve as the building blocks of a Java program's architecture.

The primary method in any class is the `main` method. When you run a Java application, the `main` method is the initial point of execution.
The syntax `public class SphereVolumeCalculator` declares a new class, while everything inside curly braces belongs to that class.
Understanding Java classes helps manage and organize code efficiently, making it more readable and maintainable.

Java Methods

Methods in Java are blocks of code that perform a specific task. They structure and encapsulate pieces of functionality, allowing for code reusability.
In the context of our problem, the `sphereVolume` method is defined to calculate volume based on a passed radius.

• Method Signature: The method signature `public static double sphereVolume(double radius)` defines access level, return type, name, and parameters.
• Access Modifiers: The `public` keyword makes it accessible from other classes. `static` means it belongs to the class rather than any object instance.
• Return Type: `double` indicates what kind of output the method will provide after execution.

Methods not only perform operations but also enhance the readability and modularization of code.
For example, giving a meaningful name like `sphereVolume` describes its purpose instantly, aiding in maintaining and testing the application.

User Input Handling

Handling user input effectively is crucial for interactive Java applications. This task becomes straightforward through the `Scanner` class.
The `Scanner` class reads input from the user's keyboard and converts it into a format your program can use.

• Creating Scanner: Initiate the scanner using `Scanner scanner = new Scanner(System.in);` to allow user interaction.
• Prompting: Use `System.out.print("Enter the radius of the sphere: ");` to request user input.
• Reading Input: `double radius = scanner.nextDouble();` reads the input and stores it as a double variable.
• Resource Management: Closing resources using `scanner.close();` is vital to free up system resources post-usage.

This process ensures smooth communication between the user and the application, enhancing the overall user experience.

Mathematical Calculations in Java

Mathematical calculations are a common requirement in many Java programs, utilizing its robust mathematical library.
In this exercise, we calculate the volume of a sphere using a specific formula.

• Formula Usage: The formula to calculate sphere volume is \( \frac{4}{3} \pi r^3 \).
• Built-in Constants: Java’s `Math.PI` provides an accurate value of \( \pi \).
• Exponentiation: Use `Math.pow(radius, 3)` to raise the radius to the power of three.
• Precision: Multiplication operations like `(4.0 / 3.0)` ensure the calculation returns a precise `double` value.

By leveraging Java's built-in Math functions, we can perform complex calculations with ease, maintaining accuracy and efficiency.
This computational power is crucial in scientific, statistical, and financial applications, where precise results are a must.