ybq/Android-SpinKit · error · IllegalStateException

The fractions.length must equal values.length…

Error message

The fractions.length must equal values.length, fraction.length[%d], values.length[%d]

What it means

SpriteAnimatorBuilder.validate/holder builds keyframe animations where each fraction (0-1 keyframe position) must pair one-to-one with an animated value. ensurePair throws IllegalStateException when the fractions array and values array lengths differ, because PropertyValuesHolder cannot map frames to values unambiguously.

Solutions

Make fractions.length exactly equal to values.length in the builder call
Ensure the last fraction is 1f and the first is 0f (first/last must always pair)
Copy an existing Sprite implementation (e.g. Wave) as a template for correct fraction/value pairing
If generating arrays programmatically, assert fractions.length == values.length before constructing the builder

Example fix

// before
new SpriteAnimatorBuilder(this).floatInt(new float[]{0f, 0.5f, 1f}, 0, 255); // 3 fractions, 2 values
// after
new SpriteAnimatorBuilder(this).floatInt(new float[]{0f, 0.5f, 1f}, 0, 255, 0); // 3 fractions, 3 values

Defensive patterns

Strategy: validation

Validate before calling

if (fractions.length != values.length) throw new IllegalArgumentException("fractions and values must have equal length");
new SpriteAnimatorBuilder(sprite).floatInt(fractions, values...);

Try / catch

try { builder.floatInt(fractions, v0, v1, v2); } catch (IllegalStateException e) { Log.e(TAG, "Keyframe arrays length mismatch", e); }

Prevention

Pair every keyframe fraction with exactly one value; count them before building
Always start fractions at 0f and end at 1f with a value for each
Model custom sprites on the library's built-in Sprite implementations
Add a unit test asserting fraction/value array lengths for each custom sprite

When it happens

Trigger: Chaining SpriteAnimatorBuilder methods like floatInt(0, 1, ...) or alpha(float[], ...) with a fractions array whose length differs from the values array, e.g. alpha(0.5f) with two values or fractions {0,0.5,1} with two values.

Common situations: Hand-writing keyframes for a custom spinner sprite and miscounting: forgetting the terminal fraction of 1.0, or adding an extra value for a bounce effect without a matching fraction.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

this d must be instanceof Sprite

AI-assisted analysis of ybq/Android-SpinKit@aa83e4d0a4 (2026-09-12). Data as JSON: /api/errors/ec5a36d39549d136. Report an issue: GitHub.

Appendix: source

Thrown at library/src/main/java/com/github/ybq/android/spinkit/animation/SpriteAnimatorBuilder.java:135

    public SpriteAnimatorBuilder translateYPercentage(float[] fractions, Float... translateYPercentage) {
        holder(fractions, Sprite.TRANSLATE_Y_PERCENTAGE, translateYPercentage);
        return this;
    }

    private void holder(float[] fractions, Property property, Float[] values) {
        ensurePair(fractions.length, values.length);
        fds.put(property.getName(), new FloatFrameData(fractions, property, values));
    }


    private void holder(float[] fractions, Property property, Integer[] values) {
        ensurePair(fractions.length, values.length);
        fds.put(property.getName(), new IntFrameData(fractions, property, values));
    }

    private void ensurePair(int fractionsLength, int valuesLength) {
        if (fractionsLength != valuesLength) {
            throw new IllegalStateException(String.format(
                    Locale.getDefault(),
                    "The fractions.length must equal values.length, " +
                            "fraction.length[%d], values.length[%d]",
                    fractionsLength,
                    valuesLength));
        }
    }


    public SpriteAnimatorBuilder interpolator(Interpolator interpolator) {
        this.interpolator = interpolator;
        return this;
    }

    public SpriteAnimatorBuilder easeInOut(float... fractions) {
        interpolator(KeyFrameInterpolator.easeInOut(
                fractions
        ));

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