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();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
- k; F# }+ S8 P' _: o  U; D1 X    // executed in a specific order, but these steps should
" E' e4 i8 O5 U+ O# M    // 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.
4 M0 i/ m7 k. ?5 C9 Y        
, {8 a* e$ E8 V$ H& o- g    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
, k1 G, C# J9 r) |" ~: ?8 C    // changes the heatbugs have made. The ordering here is
# K- q# ?1 w* L* }    // significant!
        
/ d/ P! D( F1 S7 U1 r+ D    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
; u" Z4 J. |" m  q1 C    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
& ~) J2 I: G& ~    // 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).
, e. @# }) }' n) _# ^   
    modelActions = new ActionGroupImpl (getZone ());
4 A/ n5 L  x3 J, r8 {
    try {
# w" h; q) I8 }' n0 N$ n% D. V      modelActions.createActionTo$message
& n% _& |4 O0 ~6 b" ]        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
$ |0 M' B, X0 U7 \      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
3 q* t+ O7 F0 W0 z* Q0 i1 ^3 c
9 n" `7 ?$ D4 N$ ^( n0 f' `& x4 r9 v" k    try {
# x( o1 O" C: x/ a  o- K7 c# _      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
3 ^9 Q7 \4 L% z- f7 d& Y      actionForEach =
" Q) C% u( \3 b( B        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
! m$ m& X4 Q7 i- p; Z/ `/ d                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
- D- f; [' A  v6 N6 |, j  C& W    }
9 r. n) x) @4 c' Q  R% L   
- L+ d4 N; z2 ?    syncUpdateOrder ();
% d# H$ V$ u4 W1 o% [
    try {
      modelActions.createActionTo$message
3 Z8 a# Q+ ]# u4 u% X- k        (heat, new Selector (heat.getClass (), "updateLattice", false));
+ z2 c7 [" x6 y/ z    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
. Y! c- B% F2 X" \2 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
    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

$ p7 M! E  H# L2 M8 F2 g    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
/ o9 V& c" d2 m8 Q    // complicated schedules.
  
, S: o6 S% ]8 z$ i' f  X    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
* s( R7 b* g% k1 V/ J  }