Java Encapsulation: Implementing a circle class with getter, setter, and calculation methods

Java Encapsulatiion: Exercise-5 with Solution

Write a Java program to create a class called Circle with a private instance variable radius. Provide public getter and setter methods to access and modify the radius variable. However, provide two methods called calculateArea() and calculatePerimeter() that return the calculated area and perimeter based on the current radius value.

Sample Solution:

Java Code:

// Circle.java
// Circle Class

class Circle {
  private double radius;

  public double getRadius() {
    return radius;
  }

  public void setRadius(double radius) {
    this.radius = radius;
  }

  public double calculateArea() {
    return Math.PI * radius * radius;
  }

  public double calculatePerimeter() {
    return 2 * Math.PI * radius;
  }
}

// Main.java
// Main Class

public class Main {
  public static void main(String[] args) {
    // Create an instance of Circle
    Circle circle = new Circle();

    // Set the radius using the setter method
    circle.setRadius(7.0);

    // Get the radius using the getter method
    double radius = circle.getRadius();

    // Calculate and print the area and perimeter
    double area = circle.calculateArea();
    double perimeter = circle.calculatePerimeter();

    System.out.println("Circle Radius: " + radius);
    System.out.println("Circle Area: " + area);
    System.out.println("Circle Perimeter: " + perimeter);
  }
}

Sample Output:

Circle Radius: 7.0
Circle Area: 153.93804002589985
Circle Perimeter: 43.982297150257104

Explanation:

In the above exercise,

In this code, the Circle class encapsulates the private instance variable radius. The getRadius() and setRadius() methods are public getter and setter methods that allow other classes to access and modify radius values, respectively.

Additionally, the Circle class provides two public methods calculateArea() and calculatePerimeter() that calculate and return the area and perimeter of the circle. These methods are based on the current radius value. These methods use the formula Math.PI*radius*radius for area calculation and 2*Math.PI*radius for perimeter calculation.

In the Main class, an object circle of the Circle class is created. The circle radius is set using the setRadius() method, and then retrieved using the getRadius() method.

The area and perimeter of the circle are calculated using the calculateArea() and calculatePerimeter() methods, respectively, and printed using System.out.println().

Flowchart:

Java Code Editor:

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