可能的解释：

1. 您的默认语言环境与输入日期不兼容 - 例如它不能理解 Sep 作为月份名称


2. 输入字符串有问题，或


3. t 是错误的类型（例如 java.sql.Date 而不是 java.util.Date 或其他一些类型）或未声明。

1. your default locale is incompatible with the input date - e.g. it can't understand Sep as a month name
2. there's something wrong with the input string, or
3. t is the wrong type (e.g. java.sql.Date instead of java.util.Date, or some other type altogether), or is not declared.

您应该包括你的问题的异常的细节，以弄清楚它是什么，但这里是一个工作示例，使用基本上你自己的代码，添加了一个特定的 Locale 。

You should include details of the exception in your question to figure out which it is, but here's a working example using basically your own code, with the addition of a specific Locale.

SimpleDateFormat ft = new SimpleDateFormat("MMM dd, yyyy hh:mm:ss a", Locale.US);
java.util.Date t=ft.parse("Sep 16, 2015 10:34:23 AM");
ft.applyPattern("MM.dd");
System.out.println(ft.format(t));

输出：

09.16