MuntashirAkon/AppManager · error · IllegalArgumentException

Buffer size %,d must be at least

Error message

Buffer size %,d must be at least %s for a CharsetEncoder %s.

What it means

checkMinBufferSize() verifies the caller-provided buffer size is at least maxBytesPerChar as reported by the CharsetEncoder (minBufferSize). A smaller buffer cannot guarantee a single character always fits, so the constructor throws IllegalArgumentException with the required minimum and charset name.

Solutions

1. Use the CharSequenceInputStream(CharSequence, Charset) constructor that computes a safe default buffer size.
2. Query the required minimum via the library's minBufferSize logic (encoder.maxBytesPerChar()) and pass at least that value.
3. Use a comfortably larger buffer (e.g. 8192) instead of tuning minimal sizes.

Example fix

// before
new CharSequenceInputStream(cs, charset, 16);
// after
int min = (int) charset.newEncoder().maxBytesPerChar();
new CharSequenceInputStream(cs, charset, Math.max(min, 8192));

float min = charset.newEncoder().maxBytesPerChar();
if (bufferSize < min) bufferSize = Math.max((int) min, 8192);

When it happens

Trigger: Constructing CharSequenceInputStream with an explicit bufferSize smaller than minBufferSize(charsetEncoder) — e.g. a 16-byte buffer with a UTF-16 encoder whose max per-char size is larger.

Common situations: Hand-tuning tiny buffers for memory savings without checking the charset's maxBytesPerChar; switching charsets (e.g. UTF-8 to UTF-16) while keeping the same buffer size.

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

• Bad mode
• buffersize must be bigger than 0
• count must not be negative or greater than " +…
• len(" + len + ") < 0.
• len(" + len + ") < 0.

AI-assisted analysis of MuntashirAkon/AppManager@0152f468fc (2026-09-12). Data as JSON: /api/errors/5ba087990043a945. Report an issue: GitHub.

Appendix: source

Thrown at libcore/io/src/main/java/io/github/muntashirakon/io/CharSequenceInputStream.java:250

    @Override
    public long skip(long n) throws IOException {
        //
        // This could be made more efficient by using position to skip within the current buffer.
        //
        long skipped = 0;
        while (n > 0 && available() > 0) {
            read();
            n--;
            skipped++;
        }
        return skipped;
    }

    private static int checkMinBufferSize(final CharsetEncoder charsetEncoder, final int bufferSize) {
        final float minRequired = minBufferSize(charsetEncoder);
        if (bufferSize < minRequired) {
            throw new IllegalArgumentException(String.format("Buffer size %,d must be at least %s for a CharsetEncoder %s.", bufferSize, minRequired,
                    charsetEncoder.charset().displayName()));
        }
        return bufferSize;
    }

    private static float minBufferSize(final CharsetEncoder charsetEncoder) {
        return charsetEncoder.maxBytesPerChar() * 2;
    }
}

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