public static void writeStringFixedSize(final DataOutput out, String s, int size)
            throws IOException {
        byte[] b = toBytes(s);
        if (b.length > size) {
            throw new IOException("Trying to write " + b.length + " bytes (" + toStringBinary(b)
                                  + ") into a field of length " + size);
        }

        out.writeBytes(s);
        for (int i = 0; i < size - s.length(); ++i) {
            out.writeByte(0);
        }
    }
Writes a string as a fixed-size field, padded with zeros.
stroom-bytebuffer/src/main/java/stroom/bytebuffer/hbase/Bytes.java