Use String.format (or java.util.Formatter):
Timestamp timestamp = ...
String.format("%1$TD %1$TT", timestamp)
EDIT:
please see the documentation of Formatter to know what TD and TT means: click on java.util.Formatter
The first 'T' stands for:
't', 'T' date/time Prefix for date and time conversion characters.
and the character following that 'T':
'T' Time formatted for the 24-hour clock as "%tH:%tM:%tS".
'D' Date formatted as "%tm/%td/%ty".