code: public char next(char c) throws JSONException {
  		char n = this.next();
  		if (n != c) {
  			throw this.syntaxError("Expected '" + c + "' and instead saw '" + n + "'");
  		}
  		return n;
  	}
docs: 读取下一个字符，并比对是否和指定字符匹配
  
  @param c 被匹配的字符
  @return The character 匹配到的字符
  @throws JSONException 如果不匹配抛出此异常