convert System.currentTimeMillis() to java.utils.Date object.

convert_to_date.pde

import java.util.*;

void setup() {
  long t_start = 1393640607018L;
  
  long t_1130 = 1393641000000L;
  long t_1200 = 1393642800000L;
  long t_1230 = 1393644600000L;
  long t_1300 = 1393646400000L;

  long t_last = 1393656236540L;

  println(t_start + " -> " + new Date(t_start));
  println(t_1130 + " -> " + new Date(t_1130));
  println(t_1200 + " -> " + new Date(t_1200));
  println(t_1230 + " -> " + new Date(t_1230));
  println(t_1300 + " -> " + new Date(t_1300));
  println(t_last + " -> " + new Date(t_last));
}

result.txt

1393640607018 -> Sat Mar 01 11:23:27 JST 2014
1393641000000 -> Sat Mar 01 11:30:00 JST 2014
1393642800000 -> Sat Mar 01 12:00:00 JST 2014
1393644600000 -> Sat Mar 01 12:30:00 JST 2014
1393646400000 -> Sat Mar 01 13:00:00 JST 2014
1393656236540 -> Sat Mar 01 15:43:56 JST 2014