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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( A2 e/ `* t5 a) n% B4 v$ d public Object buildActions () {
    super.buildActions();
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& [) F  y. Y+ e2 C    // Create the list of simulation actions. We put these in
    // 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
8 o# r3 m7 k0 B( V2 k  J    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
1 B; Y5 w, Z8 D        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
+ G  {% p2 t2 K. B" }) _    // changes the heatbugs have made. The ordering here is
* M. M3 r1 o& G" w- K    // significant!
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    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
4 ^( J( F% x7 W* V' n7 q' m    // randomize the order in which the bugs actually run
0 u5 p' m. v1 Y+ i% c2 u5 y    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
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; q7 [: T0 m  v( m    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
6 Z4 `$ y1 |% H8 @$ \) I    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
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    try {
7 W7 {' {) H+ E1 m      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
- y" t! K8 I9 N* K2 ~3 @% w" x' f    }
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1 @( V  ]: Y7 [3 y! `    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
& j3 y- D# u- H# N      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
. K2 G/ x+ ]3 e         new FCallImpl (this, proto, sel,
( v) X0 A4 s/ E) Y# ]* U) o4 y" E                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
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    syncUpdateOrder ();
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    try {
( g( |# R8 r4 d! P      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 t+ Z/ o; E7 m" u7 `6 q' G    } catch (Exception e) {
, b* s# l- k9 @5 m0 P      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // 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
# h: K8 S. D  Z3 j1 }    // modelActions ActionGroup at particular times.  This
+ a7 y: T; y2 X8 C( B    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
+ n5 `' a. g8 Q6 l; v) i/ o    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
& ]) y) |" |! C  j3 h# G, w; c    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
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# F$ Y0 t! N3 {: t/ |    return this;
  }