考虑以下代码:
void main() {
  var duration = new Duration(days : 1);
  print ("duration " + duration.toString());
  var d1 = new DateTime(2014, 10, 26);
  print ("d1 " + d1.toString());
  d1 = d1.add(duration);
  print ("d1 + duration " + d1.toString());
  var d2 = new DateTime(2014, 10, 20);
  print ("d2 " + d2.toString());
  d2 = d2.add(duration);
  print ("d2 + duration " + d2.toString());
}
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和输出:
duration 24:00:00.000000
d1 2014-10-26 00:00:00.000
d1 + duration 2014-10-26 23:00:00.000
d2 2014-10-20 00:00:00.000
d2 + duration 2014-10-21 00:00:00.000 …Run Code Online (Sandbox Code Playgroud) dart ×1