StringBuffer sb = new StringBuffer(); for (int i = 1; i <= 1234; i++) { sb.append(i); } String s = sb.toString(); int sum = 0; for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); String ss = String.valueOf(c); int j = Integer.valueOf(ss); sum+=j; } System.out.println(sum); 结果为:15895