public boolean startsWith(String prefix, int toffset) {
        // Note: toffset might be near -1>>>1.
        if (toffset < 0 || toffset > length() - prefix.length()) {
            return false; //这是指寻找位置小于0或大于字符串长度返回false吗， length() - prefix.length()这指的是字符串长度吗为什么要- prefix.length()
        }
        byte ta[] = value; //这ta[]指向哪啊
        byte pa[] = prefix.value; //.value是啥意思
        int po = 0;
        int pc = pa.length;
        if (coder() == prefix.coder()) { //这个if语块干什么呀
            int to = isLatin1() ? toffset : toffset << 1;
            while (po < pc) {
                if (ta[to++] != pa[po++]) {
                    return false;
                }
            }
        } else {
            if (isLatin1()) { // && pcoder == UTF16 //这个if又干什么了
                return false;
            }
            // coder == UTF16 && pcoder == LATIN1)
            while (po < pc) {
                if (StringUTF16.getChar(ta, toffset++) != (pa[po++] & 0xff)) {
                    return false; //这个if我也不明白
               }
            }
        }
        return true;
    }