Resetting the time part of a timestamp in Java

Question

In Java, given a timestamp, how to reset the time part alone to 00:00:00 so that the timestamp represents the midnight of that particular day ?

In T-SQL, this query

Answer 1

Using Calendar.set() would certanly be "by the book" solution, but you might also use java.sql.Date:

java.util.Date originalDate = new java.util.Date();
java.sql.Date wantedDate = new java.sql.Date(originalDate.getTime());

That would do exactly what you want since:

To conform with the definition of SQL DATE, the millisecond values wrapped by a java.sql.Date instance must be 'normalized' by setting the hours, minutes, seconds, and milliseconds to zero in the particular time zone with which the instance is associated.

Since java.sql.Date extends java.util.Date, you can freely use it as such. Be aware that wantedDate.getTime() will retrieve original timestamp though - that's why you don't want to create another java.util.Date from java.sql.Date!