} int strLen = str.length(); if (strLen > 0) { int len = length(); ensureCapacity(len + strLen); str.getChars(0, strLen, buffer, len); size += strLen; } return this;
} return append(obj.toString());
    public StrBuilder append(String str) {        if (str == null) {            return appendNull();        }        int strLen = str.length();        if (strLen > 0) {            int len = length();            ensureCapacity(len + strLen);            str.getChars(0, strLen, buffer, len);            size += strLen;        }        return this;    }