public String nextLine() {
        if (hasNextPattern == linePattern())
            return getCachedResult();
        clearCaches();

        String result = findWithinHorizon(linePattern, 0);
        if (result == null)
            throw new NoSuchElementException("No line found");
        MatchResult mr = this.match();
        String lineSep = mr.group(1);
        if (lineSep != null)
            result = result.substring(0, result.length() - lineSep.length());
        if (result == null)
            throw new NoSuchElementException();
        else
            return result;
    }

------解决方案--------------------
System.in系统预设的为BufferedInputStream
System.in.read()读取的是你输入字符串中的第一个字节值
而Scanner scan=new Scanner(System.in);
Java code
public Scanner(InputStream source) {
   this(new InputStreamReader(source), WHITESPACE_PATTERN);
}