View Compilation Error

0_0_12842965_24468\Main.java:30: 非法的类型开始
			ArrayList<Period> h_m = new ArrayList<>();
			                                      ^
0_0_12842965_24468\Main.java:36: 非法的类型开始
			ArrayList<Period> h_s = new ArrayList<>();
			                                      ^
0_0_12842965_24468\Main.java:42: 非法的类型开始
			ArrayList<Period> m_s = new ArrayList<>();
			                                      ^
0_0_12842965_24468\Main.java:50: 非法的类型开始
			ArrayList<Period> temp = new ArrayList<>();
			                                       ^
4 错误