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Java Exercises: Find the area and perimeter of a circle

Java Basic: Exercise-11 with Solution

Write a Java program to print the area and perimeter of a circle.

In geometry, the area enclosed by a circle of radius r is πr2. Here the Greek letter π represents a constant, approximately equal to 3.14159, which is equal to the ratio of the circumference of any circle to its diameter.

The circumference of a circle is the linear distance around its edge.

Pictorial Presentation:

Java area and perimeter of a circle

Why is the area of a circle of a circle pi times the square of the radius? 


Why is the area of a circle of a circle pi times the square of the radius?

Sample Solution:

Java Code:


public class Exercise11 {
 
   private static final double radius = 7.5;

    public static void main(String[] args) {

        double perimeter = 2 * Math.PI * radius;
        double area = Math.PI * radius * radius;

        System.out.println("Perimeter is = " + perimeter);
        System.out.println("Area is = " + area);
    }
}

Sample Output:

Perimeter is = 47.12388980384689                                                                              
Area is = 176.71458676442586

Flowchart:

Flowchart: Java exercises: Find the area and perimeter of a circle

Sample Solution:

Java Code:

import java.util.Scanner;
public class Main {
 public static void main(String[] args) {
  Scanner io = new Scanner(System.in);
  System.out.println("Input the radius of the circle: ");
  double radius = io.nextDouble();
  System.out.println("Perimeter is = " + (2 * radius * Math.PI));
  System.out.println("Area is = " + (Math.PI * radius * radius));
 }
}

Sample Output:

Input the radius of the circle: 
 5
Perimeter is = 31.41592653589793
Area is = 78.53981633974483

Flowchart:

Flowchart: Java exercises: Find the area and perimeter of a circle

Java Code Editor:

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Java: Tips of the Day

countOccurrences

Counts the occurrences of a value in an array.

Use Arrays.stream().filter().count() to count total number of values that equals the specified value.

public static long countOccurrences(int[] numbers, int value) {
    return Arrays.stream(numbers)
            .filter(number -> number == value)
            .count();
}

Ref: https://bit.ly/3kCAgLb