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：
% j8 k9 j4 [+ E6 \) n
& m' q7 S- m2 v  n% [+ F public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
- Q; e1 n# K0 w3 l    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
6 c8 |0 |  N$ a( Q& h    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
0 E, ?5 X; G5 @7 j$ W1 ~8 I1 ]    // object, or ForEach object in a collection.
; U: f9 c* m/ b+ [& }) }4 i        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
2 ]" _) ]  G0 d+ G; w        
; o# J; \& u, h& b" O$ L, v    // Note also, that with the additional
8 E/ Y% k1 x7 D9 @, a1 `    // `randomizeHeatbugUpdateOrder' Boolean flag we can
6 P) ?, G& p" J* J5 {9 i    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

. R. `& r- {% n4 n    try {
# R8 y0 i! g! K0 e      modelActions.createActionTo$message
; {2 C- u) ^% \        (heat, new Selector (heat.getClass (), "stepRule", false));
- X1 l+ |! b( ^/ b/ N  O    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
" t% y: \! k$ z. Y5 [
  o$ n# i( ]+ c4 C( B# D    try {
1 G$ T! {& K: _4 L) b      Heatbug proto = (Heatbug) heatbugList.get (0);
% s8 Q8 C3 }- O/ r8 G) |- T' o9 E      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
/ S" ]& Y; V- w0 j6 }        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
6 B9 _7 R1 g. B5 M- V4 a( A      e.printStackTrace (System.err);
    }
   
3 C" Z5 x* a; m9 j8 ~) d" I' D    syncUpdateOrder ();
9 k8 D- H& d7 Y6 t6 `
    try {
# U6 \9 A0 T9 i8 X      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
" h4 C3 B) |& w1 g* W    }
) L) x) {! ^4 N1 G2 Z        
    // Then we create a schedule that executes the
+ P$ R  V3 P- J4 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
( y5 y: K+ u# i1 k, s* ^9 w! {    // 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
3 O* F! E* W/ A: ?    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
8 ]$ Q: Q: ^" ?0 K    // complicated schedules.
. `. `! L2 o; M  
    modelSchedule = new ScheduleImpl (getZone (), 1);
, f1 _; }9 M* t3 h' f. k! Y    modelSchedule.at$createAction (0, modelActions);
# X0 E- B5 f6 i- U) n* R        
    return this;
  }