以下代码，我希望x轴旋转45度，但没有任何反应。为什么呢？
a=c('2017-05-15 09:28:38 GMT', '2017-05-16 14:02:19 GMT', '2017-05-20 03:02:49 GMT', '2017-05-21 17:40:47 GMT', '2017-05-23 20:23:47 GMT', '2017-05-24 21:01:07 GMT', '2017-05-26 12:50:18 GMT', '2017-05-27 05:39:55 GMT', '2017-05-30 03:56:31 GMT', '2017-06-01 15:44:49 GMT', '2017-06-02 17:07:06 GMT', '2017-06-05 19:01:09 GMT', '2017-06-07 16:14:02 GMT', '2017-06-08 16:51:22 GMT', '2017-06-11 14:51:42 GMT', '2017-06-11 19:41:17 GMT', '2017-06-14 20:59:10 GMT', '2017-06-17 18:32:42 GMT', '2017-06-17 19:13:10 GMT', '2017-06-24 22:14:49 GMT', '2017-06-27 20:50:54 GMT', '2017-06-27 23:42:34 GMT', '2017-07-06 17:36:37 GMT', '2017-07-10 23:39:39 GMT', '2017-07-18 03:05:25 GMT', '2017-07-20 16:59:55 GMT', '2017-07-24 03:57:07 GMT', '2017-08-13 20:15:11 GMT', '2016-11-21 15:35:23 GMT', '2016-11-23 20:24:24 GMT', '2016-11-24 16:30:47 GMT', '2016-11-24 21:54:08 GMT', '2016-12-02 17:07:12 GMT', '2016-12-05 19:10:26 GMT', '2016-12-06 11:00:45 GMT', '2016-12-06 23:35:13 GMT', '2016-12-09 00:58:07 GMT', '2016-12-19 01:41:55 GMT', '2016-12-19 21:58:19 GMT', '2016-12-22 16:42:25 GMT', '2016-12-23 05:50:15 GMT', '2016-12-24 10:10:42 GMT', '2016-12-24 13:51:36 GMT', '2016-12-25 12:53:51 GMT', '2016-12-27 21:26:21 GMT', '2017-01-04 07:37:26 GMT', '2017-01-04 15:08:49 GMT', '2017-01-05 16:10:41 GMT', '2017-01-06 04:19:33 GMT', '2017-01-06 23:18:08 GMT', '2017-01-09 16:52:27 GMT', '2017-01-12 18:20:21 GMT', '2017-01-13 10:49:40 GMT', '2017-01-13 18:54:39 GMT', '2017-01-22 13:25:32 GMT', '2017-01-23 06:31:25 GMT', '2017-01-23 19:26:42 GMT', '2017-01-23 21:17:51 GMT', '2017-01-25 07:21:29 GMT', '2017-01-25 19:13:47 GMT', '2017-01-28 11:41:20 GMT', '2017-01-29 07:48:43 GMT', '2017-01-30 21:31:50 GMT', '2017-01-31 08:42:57 GMT', '2017-02-03 22:37:24 GMT', '2017-02-04 15:33:58 GMT', '2017-02-04 19:22:24 GMT', '2017-02-07 04:14:46 GMT', '2017-02-09 02:42:09 GMT', '2017-02-11 18:26:45 GMT', '2017-02-12 14:15:23 GMT', '2017-02-16 12:35:03 GMT', '2017-02-16 21:46:43 GMT', '2017-02-20 12:30:13 GMT', '2017-02-20 14:22:10 GMT', '2017-02-22 08:53:34 GMT', '2017-02-22 19:56:49 GMT', '2017-02-22 22:43:13 GMT', '2017-02-22 23:14:48 GMT', '2017-02-27 14:19:04 GMT', '2017-02-28 18:21:30 GMT', '2017-03-02 19:06:14 GMT', '2017-03-02 22:29:09 GMT', '2017-03-03 04:39:49 GMT', '2017-03-03 22:33:46 GMT', '2017-03-07 06:47:34 GMT', '2017-03-07 09:25:16 GMT', '2017-03-08 12:44:21 GMT', '2017-03-08 23:40:59 GMT', '2017-03-10 21:39:40 GMT', '2017-03-10 22:57:22 GMT', '2017-03-12 19:10:41 GMT', '2017-03-19 20:39:21 GMT', '2017-03-20 19:48:41 GMT', '2017-03-20 20:44:55 GMT', '2017-03-22 08:48:24 GMT', '2017-03-22 09:03:59 GMT', '2017-03-23 23:33:34 GMT', '2017-03-24 14:53:31 GMT', '2017-03-27 23:42:08 GMT', '2017-03-28 14:41:53 GMT', '2017-03-30 15:54:30 GMT', '2017-04-04 08:37:43 GMT', '2017-04-06 12:14:19 GMT', '2017-04-07 01:02:23 GMT', '2017-04-08 01:09:43 GMT', '2017-04-12 14:24:11 GMT', '2017-04-13 11:06:43 GMT', '2017-04-15 03:50:58 GMT', '2017-04-18 23:16:03 GMT', '2017-04-19 11:36:27 GMT', '2017-04-19 23:14:05 GMT', '2017-04-21 21:57:46 GMT', '2017-04-23 01:17:12 GMT', '2017-04-24 19:08:23 GMT', '2017-04-24 20:00:19 GMT', '2017-04-24 23:06:57 GMT', '2017-04-26 13:14:51 GMT', '2017-04-27 16:48:10 GMT', '2017-04-28 10:26:11 GMT', '2017-05-01 11:21:27 GMT', '2017-05-01 18:37:55 GMT', '2017-05-02 20:36:20 GMT', '2017-05-08 19:02:54 GMT', '2017-05-10 16:00:20 GMT', '2017-05-10 21:36:27 GMT', '2017-05-18 13:16:55 GMT', '2017-05-19 22:55:38 GMT', '2017-05-21 09:10:22 GMT', '2017-05-22 06:17:33 GMT', '2017-05-22 08:34:26 GMT', '2017-05-28 21:09:29 GMT', '2017-05-29 14:40:20 GMT', '2017-05-30 02:17:38 GMT', '2017-06-01 20:41:41 GMT', '2017-06-03 17:33:17 GMT', '2017-06-05 12:13:21 GMT', '2017-06-05 12:16:25 GMT', '2017-06-05 20:28:17 GMT', '2017-06-10 14:19:52 GMT', '2017-06-10 21:29:37 GMT', '2017-06-16 07:26:04 GMT', '2017-06-17 03:31:37 GMT', '2017-06-19 12:12:42 GMT', '2017-06-20 01:42:28 GMT', '2017-07-01 18:35:31 GMT', '2017-07-02 23:14:19 GMT', '2017-07-11 14:29:22 GMT', '2017-07-17 18:18:19 GMT', '2017-07-25 14:37:00 GMT', '2009-08-17 10:34:59 GMT')
hist(as.POSIXct(a,format="%Y-%m-%d %H:%M:%S", tz = "GMT"), breaks=20, xaxt='n')
axis.POSIXct(1, at=seq(as.Date("2010-01-01"), as.Date("2018-01-01"), , length.out=10), format="%Y-%m-%d", srt=45, adj=1, xpd=TRUE, cex.axis = 1)
答案 0 :(得分：0)
尝试las = 2而不是srt = 45：
String sql = "select * from assignment where username='"+username+"';";