I have a Date . I want to copy its time only, excluding the date. I then need to insert the time into another date.
Is there a easy way to do this?. I cant change the Date datatype. I can do, getHour(),getMinutes() etc however this is long winded. is there a clearner version that i could use ? or perhaps other library's like apache commons to set/get date time (have not spotten anything so far).
Try this:
public static Date copyTimeOnly(Date toDate, Date fromDate) { Calendar toCal = new GregorianCalendar(); toCal.setTime(toDate); Calendar fromCal = new GregorianCalendar(); fromCal.setTime(fromDate); // Copy time only toCal.set(Calendar.HOUR_OF_DAY, fromCal.get(Calendar.HOUR_OF_DAY)); toCal.set(Calendar.MINUTE, fromCal.get(Calendar.MINUTE)); toCal.set(Calendar.SECOND, fromCal.get(Calendar.SECOND)); toCal.set(Calendar.MILLISECOND, fromCal.get(Calendar.MILLISECOND)); return toCal.getTime(); } If you just need the time part of your Date object and you can't use Java 8 and don't want to use any third party framework, then use Calendar:
Calendar c = Calendar.getInstance(); c.setTime(yourDate); c.set(Calendar.YEAR, 0); c.set(Calendar.MONTH, 0); c.set(Calendar.DAY, 0); Date timeOnly = c.getTime(); or if you can use third party libraries(in this case org.apache.commons.lang3.time) you could do it this way:
private Date truncate(Date pDate) { return DateUtils.truncate(pDate, Calendar.DATE); } 
LocalTimeThe old java.util.Date/.Calendar have no class to represent a time-of-day value without a date portion. In contrast, both the Joda-Time library and the new java.time package built into Java 8 (inspired by Joda-Time) offer a LocalTime class.
Here is example code using Joda-Time 2.5.
Time zone is crucial. Do you want the time of day for that moment as seen by someone in Paris, Montréal, or Kolkata?
DateTimeZone zone = DateTimeZone.forID( "America/Montreal" ); DateTime dateTime = new DateTime( yourJUDate, zone ); LocalTime localTime = dateTime.toLocalTime(); To apply that LocalTime to another DateTime, call withTime. Joda-Time uses immutable objects. So a new DateTime object is created with values based on the original.
