JavaAlgorithms/Maths/Area.java

package Maths;

/** Find the area of various geometric shapes */
public class Area {
  public static void main(String[] args) {

    /* test cube */
    assert Double.compare(surfaceAreaCube(1), 6.0) == 0;

    /* test sphere */
    assert Double.compare(surfaceAreaSphere(5), 314.1592653589793) == 0;
    assert Double.compare(surfaceAreaSphere(1), 12.566370614359172) == 0;

    /* test rectangle */
    assert Double.compare(surfaceAreaRectangle(10, 20), 200.0) == 0;

    /* test square */
    assert Double.compare(surfaceAreaSquare(10), 100.0) == 0;

    /* test triangle */
    assert Double.compare(surfaceAreaTriangle(10, 10), 50.0) == 0;

    /* test parallelogram */
    assert Double.compare(surfaceAreaParallelogram(10, 20), 200.0) == 0;

    /* test trapezium */
    assert Double.compare(surfaceAreaTrapezium(10, 20, 30), 450.0) == 0;

    /* test circle */
    assert Double.compare(surfaceAreaCircle(20), 1256.6370614359173) == 0;
    
    /* test cylinder */
    assert Double.compare(surfaceAreaCylinder(1,2), 18.84955592153876) == 0;
  }

  /**
   * Calculate the surface area of a cube.
   *
   * @param sideLength side length of cube
   * @return surface area of given cube
   */
  private static double surfaceAreaCube(double sideLength) {
    return 6 * sideLength * sideLength;
  }

  /**
   * Calculate the surface area of a sphere.
   *
   * @param radius radius of sphere
   * @return surface area of given sphere
   */
  private static double surfaceAreaSphere(double radius) {
    return 4 * Math.PI * radius * radius;
  }

  /**
   * Calculate the area of a rectangle
   *
   * @param length length of rectangle
   * @param width width of rectangle
   * @return area of given rectangle
   */
  private static double surfaceAreaRectangle(double length, double width) {
    return length * width;
  }
  
  /**
   * Calculate surface of a cylinder
   *
   * @param radius radius of the floor
   * @param height height of the cylinder.
   */
  private static double surfaceAreaCylinder(double radius, double height) {
    return 2 * (Math.PI * radius * radius + Math.PI * radius * height);
  }

  /**
   * Calculate the area of a square
   *
   * @param sideLength side length of square
   * @return area of given square
   */
  private static double surfaceAreaSquare(double sideLength) {
    return sideLength * sideLength;
  }

  /**
   * Calculate the area of a triangle
   *
   * @param base base of triangle
   * @param height height of triangle
   * @return area of given triangle
   */
  private static double surfaceAreaTriangle(double base, double height) {
    return base * height / 2;
  }

  /**
   * Calculate the area of a parallelogram
   *
   * @param base base of parallelogram
   * @param height height of parallelogram
   * @return area of given parallelogram
   */
  private static double surfaceAreaParallelogram(double base, double height) {
    return base * height;
  }

  /**
   * Calculate the area of a trapezium
   *
   * @param base1 upper base of trapezium
   * @param base2 bottom base of trapezium
   * @param height height of trapezium
   * @return area of given trapezium
   */
  private static double surfaceAreaTrapezium(double base1, double base2, double height) {
    return (base1 + base2) * height / 2;
  }

  /**
   * Calculate the area of a circle
   *
   * @param radius radius of circle
   * @return area of given circle
   */
  private static double surfaceAreaCircle(double radius) {
    return Math.PI * radius * radius;
  }
}