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refactor: Enhance docs, code, add tests in HeronsFormula (#6746)

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* refactor: Enhance docs, code, add tests in `HeronsFormula`

* Fix lint
This commit is contained in:
Hardik Pawar
2025-10-15 14:26:57 +05:30
committed by GitHub
parent d62b438fcd
commit f460c601d3
2 changed files with 173 additions and 26 deletions
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65
src/main/java/com/thealgorithms/maths/HeronsFormula.java
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@@ -1,33 +1,76 @@
package com.thealgorithms.maths;
/**
* Wikipedia for HeronsFormula => https://en.wikipedia.org/wiki/Heron%27s_formula
* Find the area of a triangle using only side lengths
* Heron's Formula implementation for calculating the area of a triangle given
* its three side lengths.
* <p>
* Heron's Formula states that the area of a triangle whose sides have lengths
* a, b, and c is:
* Area = √(s(s - a)(s - b)(s - c))
* where s is the semi-perimeter of the triangle: s = (a + b + c) / 2
* </p>
*
* @see <a href="https://en.wikipedia.org/wiki/Heron%27s_formula">Heron's
* Formula - Wikipedia</a>
* @author satyabarghav
*/
public final class HeronsFormula {
/*
* A function to get the Area of a Triangle using Heron's Formula
* @param s1,s2,s3 => the three sides of the Triangle
* @return area using the formula (√(s(s – s1)(s – s2)(s – s3)))
* here s is called semi-perimeter and it is the half of the perimeter (i.e; s = (s1+s2+s3)/2)
* @author satyabarghav
/**
* Private constructor to prevent instantiation of this utility class.
*/
private HeronsFormula() {
}
/**
* Checks if all three side lengths are positive.
*
* @param a the length of the first side
* @param b the length of the second side
* @param c the length of the third side
* @return true if all sides are positive, false otherwise
*/
private static boolean areAllSidesPositive(final double a, final double b, final double c) {
return a > 0 && b > 0 && c > 0;
}
/**
* Checks if the given side lengths satisfy the triangle inequality theorem.
* <p>
* The triangle inequality theorem states that the sum of any two sides
* of a triangle must be greater than the third side.
* </p>
*
* @param a the length of the first side
* @param b the length of the second side
* @param c the length of the third side
* @return true if the sides can form a valid triangle, false otherwise
*/
private static boolean canFormTriangle(final double a, final double b, final double c) {
return a + b > c && b + c > a && c + a > b;
}
/**
* Calculates the area of a triangle using Heron's Formula.
* <p>
* Given three side lengths a, b, and c, the area is computed as:
* Area = √(s(s - a)(s - b)(s - c))
* where s is the semi-perimeter: s = (a + b + c) / 2
* </p>
*
* @param a the length of the first side (must be positive)
* @param b the length of the second side (must be positive)
* @param c the length of the third side (must be positive)
* @return the area of the triangle
* @throws IllegalArgumentException if any side length is non-positive or if the
* sides cannot form a valid triangle
*/
public static double herons(final double a, final double b, final double c) {
if (!areAllSidesPositive(a, b, c) || !canFormTriangle(a, b, c)) {
throw new IllegalArgumentException("Triangle can't be formed with the given side lengths");
if (!areAllSidesPositive(a, b, c)) {
throw new IllegalArgumentException("All side lengths must be positive");
}
if (!canFormTriangle(a, b, c)) {
throw new IllegalArgumentException("Triangle cannot be formed with the given side lengths (violates triangle inequality)");
}
final double s = (a + b + c) / 2.0;
return Math.sqrt((s) * (s - a) * (s - b) * (s - c));