For 1280512800
, multiply by 1000, since java is expecting milliseconds:
java.util.Date time=new java.util.Date((long)timeStamp*1000);
If you already had milliseconds, then just new java.util.Date((long)timeStamp);
From the documentation:
Allocates a Date object and initializes it to represent the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.