TheAlgorithms/Java · error · IllegalArgumentException

Length must be greater than 0

Error message

Length must be greater than 0

What it means

Thrown by Area.surfaceAreaCuboid when the 'length' argument is <= 0. This is the first of three sequential guards (length, then width, then height) on the cuboid surface-area formula 2*(l*w + l*h + w*h); a non-positive length is caught before width/height are even checked.

Source

Thrown at src/main/java/com/thealgorithms/maths/Area.java:48

     */
    public static double surfaceAreaCube(final double sideLength) {
        if (sideLength <= 0) {
            throw new IllegalArgumentException("Side length must be greater than 0");
        }
        return 6 * sideLength * sideLength;
    }

    /**
     * Calculate the surface area of a cuboid.
     *
     * @param length length of the cuboid
     * @param width width of the cuboid
     * @param height height of the cuboid
     * @return surface area of given cuboid
     */
    public static double surfaceAreaCuboid(final double length, double width, double height) {
        if (length <= 0) {
            throw new IllegalArgumentException("Length must be greater than 0");
        }
        if (width <= 0) {
            throw new IllegalArgumentException("Width must be greater than 0");
        }
        if (height <= 0) {
            throw new IllegalArgumentException("Height must be greater than 0");
        }
        return 2 * (length * width + length * height + width * height);
    }

    /**
     * Calculate the surface area of a sphere.
     *
     * @param radius radius of sphere
     * @return surface area of given sphere
     */
    public static double surfaceAreaSphere(final double radius) {
        if (radius <= 0) {

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Pass length > 0 as the first argument: surfaceAreaCuboid(2, 3, 4).
2. Validate all three dimensions up front so the error names the real offender.
3. Build a small Dimensions value object that rejects non-positive values at construction.

Example fix

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

if (length <= 0 || width <= 0 || height <= 0) {
    throw new IllegalArgumentException("cuboid dimensions must be > 0");
}
double a = Area.surfaceAreaCuboid(length, width, height);

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

try {
    double a = Area.surfaceAreaCuboid(l, w, h);
} catch (IllegalArgumentException e) {
    // one of l/w/h was non-positive; identify which
}

When it happens

Trigger: surfaceAreaCuboid(0, 2, 2); surfaceAreaCuboid(-1, 2, 2); any call where the first dimension is non-positive.

Common situations: Passing a partially-populated dimensions object where length defaulted to 0; sign error in a conversion producing a negative length.

Related errors

• Side length must be greater than 0
• Width must be greater than 0
• Height must be greater than 0
• Radius must be greater than 0
• slant height must be greater than 0

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/6eb46f4956ecf6c6. Report an issue: GitHub.