问jheatbugs-2001-03-28中某些代码

sybbk

HeatbugModelSwarm中buildActions部分，3个try分别是做什么？查了下refbook-java-2.2，解释太简略，还是不懂，高手指点，谢谢！代码如下：
6 g$ v! r( W: o* S+ y6 h' J
public Object buildActions () {
3 ~) j3 S$ k2 i- Q1 f    super.buildActions();
   
    // Create the list of simulation actions. We put these in
  k9 h$ x) W- t7 Y* Y1 v    // an action group, because we want these actions to be
% q# F, y+ x3 L) x: X+ x& J    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
8 ]6 I, I  _  [* [( S* D    // object, or ForEach object in a collection.
' v0 H/ C4 O3 ~2 O$ \        
    // Note we update the heatspace in two phases: first run
6 l% ^2 Y9 G6 m, K; |; M6 b) O5 }1 ]    // diffusion, then run "updateWorld" to actually enact the
, j9 m& p' t4 J9 W    // changes the heatbugs have made. The ordering here is
    // significant!
        
# u5 p. }0 C& a7 j0 K    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
. E. l9 k/ x6 [% o    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
! i5 I% l7 R& t5 c6 `/ K) d9 K0 t( a    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
3 B. i* ?1 T  Q6 q        
; t) z  c4 n/ b% e# h2 k    // By default, all `createActionForEach' modelActions have
- E* h) P) ^4 E7 ?+ P    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
% b9 j5 e; J5 m* m    // identical (assuming the list order is not changed
9 p3 v0 D% e: Z8 X, V- O3 v    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

6 H' w" q/ z' G2 R    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

6 C1 m" ]! X2 P    try {
# M) ~( E: C3 P. I      Heatbug proto = (Heatbug) heatbugList.get (0);
6 h. M, p; X& W$ Q  V# j      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
' b( @' A8 Q# u' z        (heatbugList,
) ?1 W9 M" E- O         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
. ]( {5 `. ~& |# T6 Z0 x    } catch (Exception e) {
      e.printStackTrace (System.err);
, b% A1 [0 I# K8 {    }
   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
5 O4 X. I4 v5 k  ^/ A. l    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
; g$ A  M2 c' ~$ ^0 H, j    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
+ h4 |- x' t* r  K! `' W# J- k9 A    // the beginning of the loop.
3 V. p1 I* Y; |' r% ~; J
    // This is a simple schedule, with only one action that is
4 [! C; g- O/ p  c& c1 _* |    // just repeated every time. See jmousetrap for more
    // complicated schedules.
/ d  E- f. v# U. @  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }