Circle Program in Java

Java is a versatile and widely used programming language, and it's an excellent choice for implementing various algorithms and mathematical concepts. One such concept is working with circles. In this section, we will explore how to write a Circle program in Java, covering different approaches to achieve this and provide complete code examples.

Circles

A circle is a fundamental geometric shape defined by a set of points in a plane that are equidistant from a fixed point called the center. The distance from the center to any point on the circumference is called the radius.

Approach 1: Using Classes

The Object-Oriented Programming (OOP) paradigm in Java allows us to represent circles as objects. We will create a Circle class with attributes such as the center coordinates and radius, and then implement methods to perform operations like calculating the area and circumference.

CircleProgram.java

class Circle {
    private double centerX;
    private double centerY;
    private double radius;
    public Circle(double x, double y, double r) {
        centerX = x;
        centerY = y;
        radius = r;
    }
    public double calculateArea() {
        return Math.PI * radius * radius;
    }
    public double calculateCircumference() {
        return 2 * Math.PI * radius;
    }
}
public class CircleProgram {
    public static void main(String[] args) {
        Circle circle = new Circle(0, 0, 5);
        System.out.println("Area: " + circle.calculateArea());
        System.out.println("Circumference: " + circle.calculateCircumference());
    }
}

Output:

Area: 78.53981633974483
Circumference: 31.41592653589793

In this approach, we encapsulate the circle's properties within a class and provide methods to calculate the area and circumference. The main function demonstrates how to use this Circle class.

Approach 2: Using Functions

If we prefer a more procedural approach, you can use functions to perform circle-related calculations. In this approach, we would not define a Circle class but rather use separate functions to calculate area and circumference.

CircleProgram.java

public class CircleProgram {
    public static double calculateArea(double radius) {
        return Math.PI * radius * radius;
    }
    public static double calculateCircumference(double radius) {
        return 2 * Math.PI * radius;
    }
    public static void main(String[] args) {
        double radius = 5;
        double area = calculateArea(radius);
        double circumference = calculateCircumference(radius);
        System.out.println("Area: " + area);
        System.out.println("Circumference: " + circumference);
    }
}

Output:

Area: 78.53981633974483
Circumference: 31.41592653589793

In this approach, we pass the radius as a parameter to the functions calculateArea() and calculateCircumference() to get the desired results.

Finding The Area and Circumference of the Circle

CircleProgram2.java

import java.util.Scanner;
public class CircleProgram2 {
    public static void main(String[] args) {
        // Create a Scanner object to get user input
        Scanner scanner = new Scanner(System.in);
        // Prompt the user to enter the radius of the circle
        System.out.print("Enter the radius of the circle: ");
        double radius = scanner.nextDouble();
        // Calculate the area of the circle using the formula: ? * r^2
        double area = Math.PI * Math.pow(radius, 2);
        // Calculate the circumference of the circle using the formula: 2 * ? * r
        double circumference = 2 * Math.PI * radius;
        // Display the results
        System.out.println("Area of the circle: " + area);
        System.out.println("Circumference of the circle: " + circumference);
        // Close the Scanner to prevent resource leaks
        scanner.close();
    }
}

Conclusion

In this section, we explored two different approaches to implement a Circle program in Java: one using classes (Object-Oriented) and the other using functions (procedural). The choice of approach depends on your specific requirements and coding style preferences.

Using a class-based approach provides a more structured and encapsulated way to work with circles, while the procedural approach is simpler and may be more suitable for small-scale programs. Whichever approach we choose, Java provides the flexibility and tools to work with geometric shapes like circles effectively.

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