TheAlgorithms/Java · error · IllegalArgumentException

Base must be greater than 0

Error message

Base must be greater than 0

What it means

Thrown by Area.surfaceAreaTriangle when baseLength <= 0. Uses the POSITIVE_BASE constant ('Base must be greater than 0'). Checked before height, so a non-positive base is reported first.

Source

Thrown at src/main/java/com/thealgorithms/maths/Area.java:147

     * @return area of given square
     */
    public static double surfaceAreaSquare(final double sideLength) {
        if (sideLength <= 0) {
            throw new IllegalArgumentException("Side Length must be greater than 0");
        }
        return sideLength * sideLength;
    }

    /**
     * Calculate the area of a triangle.
     *
     * @param base   base of triangle
     * @param height height of triangle
     * @return area of given triangle
     */
    public static double surfaceAreaTriangle(final double baseLength, final double height) {
        if (baseLength <= 0) {
            throw new IllegalArgumentException(POSITIVE_BASE);
        }
        if (height <= 0) {
            throw new IllegalArgumentException(POSITIVE_HEIGHT);
        }
        return baseLength * height / 2;
    }

    /**
     * Calculate the area of a parallelogram.
     *
     * @param base   base of a parallelogram
     * @param height height of a parallelogram
     * @return area of given parallelogram
     */
    public static double surfaceAreaParallelogram(final double baseLength, final double height) {
        if (baseLength <= 0) {
            throw new IllegalArgumentException(POSITIVE_BASE);
        }

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Pass baseLength > 0: surfaceAreaTriangle(3, 4).
2. Validate base and height before calling.
3. Reject degenerate (zero-base) triangles upstream.

Example fix

// before
double a = Area.surfaceAreaTriangle(base, h);
// after
if (base <= 0 || h <= 0) throw new IllegalArgumentException("dimensions must be > 0");
double a = Area.surfaceAreaTriangle(base, h);

if (!(baseLength > 0) || !(height > 0)) {
    throw new IllegalArgumentException("triangle dimensions must be > 0");
}
double a = Area.surfaceAreaTriangle(baseLength, height);

static boolean allPositive(double... dims) {
    for (double d : dims) if (!(d > 0)) return false;
    return true;
}

try {
    double a = Area.surfaceAreaTriangle(base, h);
} catch (IllegalArgumentException e) {
    // base or height non-positive; re-check to identify which
}

When it happens

Trigger: surfaceAreaTriangle(0, 4); surfaceAreaTriangle(-3, 4); base defaulted to 0.

Common situations: Default 0.0 base field; base computed from a side length that came out 0 or negative.

Related errors

• Side length must be greater than 0
• Length must be greater than 0
• Width must be greater than 0
• Height must be greater than 0
• Radius must be greater than 0

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/a3e3467ca66db811. Report an issue: GitHub.