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：
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public Object buildActions () {
    super.buildActions();
   
! b, ?% f7 V6 D! E0 u    // Create the list of simulation actions. We put these in
4 y( j7 T, w0 T' @$ v7 [* Z    // an action group, because we want these actions to be
, T* q# N6 H( z    // 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
    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
' A1 l# ]" b7 }. ]# H2 J    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
. B) G+ q. |& P; A/ b, ^8 N    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
) k0 _: W0 q  }3 P5 k; R  u% b    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
: T7 s. p( w) T* l1 ]+ W: F+ |    // 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
, M( K* E; V+ K3 d1 t    // order of iteration through the `heatbugList' will be
& e: e* B% ]9 w7 R5 |& V: ~* R! R    // identical (assuming the list order is not changed
    // indirectly by some other process).
* h3 i0 _) I- O6 [2 ^$ x" _   
; [) H' l' a- `4 n    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
9 p) c; t/ i0 H1 j% L) [, [" Z        (heat, new Selector (heat.getClass (), "stepRule", false));
# A2 G2 C( H5 l# A" b9 I1 x    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

# i' {* `9 F* m5 _8 x5 L    try {
# B, L) k/ r+ V; H      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
) J* Q# i8 ?* f2 t# O* s2 f8 Q! b        modelActions.createFActionForEachHomogeneous$call
# q$ H: Z5 p) n        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
: t9 G/ i$ H2 @3 {- t- i* Z    }
% @* ^( H( I  ~. p/ G   
    syncUpdateOrder ();

    try {
+ z3 R8 s8 S& h) ]  }! J: Z- c& i9 }  C      modelActions.createActionTo$message
% g- z. z$ N8 l( v- |        (heat, new Selector (heat.getClass (), "updateLattice", false));
. Q. q' x) O5 a/ g' x, I    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
$ K% a; |1 f& X5 N8 Y: \6 l    }
        
4 u% Y' c9 @4 t! H4 Q2 m    // Then we create a schedule that executes the
    // 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
% k2 v' |0 A! i: `5 |    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
% n/ R8 P& v% h& P1 V1 E) U+ a    // the beginning of the loop.
9 q7 U8 l3 m! N  Z2 l) T% J
( Z" A5 ^3 ?$ m3 k    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
( V3 q) a7 g0 q- M$ r: E    // complicated schedules.
- `( A; q6 m, `4 u  
7 ^9 j. I3 Q; I& Q2 k7 H( X. a6 _    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
3 ]2 w+ _  O- ]        
    return this;
  }