TheAlgorithms/Java · error · IllegalArgumentException

width and height must be > 0

Error message

width and height must be > 0

What it means

Thrown by PerlinNoise.generatePerlinNoise when width <= 0 or height <= 0. The method allocates a width x height noise grid and indexes it per coordinate, so a non-positive dimension would create an empty/invalid array and cause downstream indexing failures; it is rejected before allocation.

Source

Thrown at src/main/java/com/thealgorithms/others/PerlinNoise.java:55

public final class PerlinNoise {
    private PerlinNoise() {
    }

    /**
     * Generate a 2D array of blended noise values normalized to [0, 1].
     *
     * @param width       width of the noise array (columns)
     * @param height      height of the noise array (rows)
     * @param octaveCount number of octaves (layers) to blend; must be >= 1
     * @param persistence per-octave amplitude multiplier in (0, 1]
     * @param seed        seed for the random base grid
     * @return a {@code width x height} array containing blended noise values in [0,
     *         1]
     */
    static float[][] generatePerlinNoise(int width, int height, int octaveCount, float persistence, long seed) {
        if (width <= 0 || height <= 0) {
            throw new IllegalArgumentException("width and height must be > 0");
        }

        if (octaveCount < 1) {
            throw new IllegalArgumentException("octaveCount must be >= 1");
        }
        if (!(persistence > 0f && persistence <= 1f)) { // using > to exclude 0 and NaN
            throw new IllegalArgumentException("persistence must be in (0, 1]");
        }
        final float[][] base = createBaseGrid(width, height, seed);
        final float[][][] layers = createLayers(base, width, height, octaveCount);
        return blendAndNormalize(layers, width, height, persistence);
    }

    /** Create the base random lattice values in [0,1). */
    static float[][] createBaseGrid(int width, int height, long seed) {
        final float[][] base = new float[width][height];
        Random random = new Random(seed);
        for (int x = 0; x < width; x++) {

View on GitHub (pinned to fdfb9a395b)

Solutions

1. Provide positive width and height (e.g. 64x64) when calling.
2. Default both dimensions to a positive value when the source is missing or zero.
3. Validate dimensions at the input boundary and fail with context there.
4. Ensure size computations (e.g. baseSize * scale) cannot collapse to 0.

Example fix

// before
float[][] noise = PerlinNoise.generatePerlinNoise(w, h, octaves, persistence, seed); // w or h may be 0

// after
int width = w > 0 ? w : 64;
int height = h > 0 ? h : 64;
float[][] noise = PerlinNoise.generatePerlinNoise(width, height, octaves, persistence, seed);

int w = width > 0 ? width : 64;
int h = height > 0 ? height : 64;
float[][] noise = PerlinNoise.generatePerlinNoise(w, h, octaveCount, persistence, seed);

public static boolean arePositiveDimensions(int w, int h) {
    return w > 0 && h > 0;
}

try {
    noise = PerlinNoise.generatePerlinNoise(w, h, oct, p, seed);
} catch (IllegalArgumentException e) {
    noise = PerlinNoise.generatePerlinNoise(64, 64, oct, p, seed);
}

When it happens

Trigger: Calling generatePerlinNoise(width, height, ...) with width <= 0 or height <= 0; dimensions sourced from config/CLI that default to 0 when unset.

Common situations: Unset dimension parameters defaulting to 0; CLI parsing returning 0; texture/tile size computed to 0 before a layout pass; negative dimension from an arithmetic error.

Related errors

• octaveCount must be >= 1
• Position must be between 0 and {array.length}
• Array is empty
• Position must be between 0 and + (array.length - 1)
• Input array should not contain negative number(s).

AI-assisted analysis of TheAlgorithms/Java@fdfb9a395b (2026-08-13). Data as JSON: /api/errors/6435d0b031755626. Report an issue: GitHub.