Java String Byte string truncation Supports garbled characters

In Java, String needs to be truncated by the number of bytes if it is an API linkage with a byte limit. In Japanese, Charaset is used for 2 bytes, 3 bytes, and so on. I thought about it for a moment, so I wrote the code as a memorandum I haven't moved it, but maybe it's okay ...

Sample.java

public static String truncateByte(String s, int length, Charset charset) {
    if (StringUtils.isEmpty(s) || length <= 0) {
    	return s == null ? null : "";
    }
    if (s.getBytes(charset).length <= length) {
    	return s;
    }
    String r = new String(s.getBytes(charset), 0, length, charset);
    while (r.length() >= 0 && !s.startsWith(r)) {
    	r = r.substring(0, r.length() - 1);
    }
    return r;
}

1. The first empty pattern is repelled
2. Keep within the number of bytes
3. Get the character truncated by the number of bytes
4. Truncate the truncated characters character by character until the original character starts with the truncated character
5. Returns the cut character