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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) T6 r1 l7 ~. v, L/ \ public Object buildActions () {
    super.buildActions();
4 t6 s0 p% ]4 m% q- }   
. f  L  a7 ~  S    // Create the list of simulation actions. We put these in
$ D- q  u2 U, o  {; x1 \$ @    // an action group, because we want these actions to be
    // 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.
% y  s/ d: \, b9 x: f" Z        
    // 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!
# O8 `5 y# [8 T2 H* u! S  n+ g( w        
0 X7 i% Y" F( l$ o! F8 t' }1 x1 t    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
8 _2 [; A- V; g6 @    // 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
* g' v/ G" o, q) |3 i2 ~    // a default order of `Sequential', which means that the
* E: j* c2 n: {+ u    // order of iteration through the `heatbugList' will be
/ W7 z7 H4 O) D7 @8 ]* F+ g* X    // identical (assuming the list order is not changed
    // indirectly by some other process).
% p- M% a7 y8 y" a: ~   
: F4 A6 i8 A. _9 M    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
) x# T5 J) C$ L! i+ r, [0 ^        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
3 o0 w7 B9 G6 P$ d; P6 Y    }
: K+ m' k. b9 U( A2 r
    try {
# ?  _! o/ ~- ]+ t5 @/ Q      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
& _3 e7 a7 I: y' A! @6 b6 L5 ?        modelActions.createFActionForEachHomogeneous$call
; o7 d$ }' Q3 f9 g) A  c3 ]5 X        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
% f5 V" E; T: v. i8 ^: A( F, d    }
, ]  a) K, v8 o# L   
    syncUpdateOrder ();

' v' d7 G+ R$ z1 u& v    try {
* [6 L1 C1 x; f) G2 i' @+ G      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
# \5 [. |% ]' e" e# Q. @    // 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.
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    // This is a simple schedule, with only one action that is
3 `0 V2 @  U- i5 R* j8 Q" v$ o' X( }3 `    // just repeated every time. See jmousetrap for more
2 T, Q* m$ R) F8 `/ l0 i5 |    // complicated schedules.
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    modelSchedule = new ScheduleImpl (getZone (), 1);
; r+ |% `& c) b0 n7 X! W1 o    modelSchedule.at$createAction (0, modelActions);
( _2 A* b4 H2 A( w" `2 w        
7 z& |1 t& S# z9 _  a9 F" F    return this;
" W$ \& j  o0 j8 f' \, e" [/ c' J  }