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
- R& C/ ^9 W" t$ R    // an action group, because we want these actions to be
3 b/ A5 _: l( s    // executed in a specific order, but these steps should
0 h# r6 o( L- q- T    // take no (simulated) time. The M(foo) means "The message
/ k# Q# e8 y0 u- g    // called <foo>". You can send a message To a particular
8 ^; R4 W! v5 }5 ?, |+ E, s4 W    // object, or ForEach object in a collection.
        
    // 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!
" v( o& l" n5 S6 U        
    // Note also, that with the additional
+ |+ J3 E* d- L( Z6 m    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
3 _) ~/ y1 D" t& G$ Q    // systematic bias in the iteration throught the heatbug
; e1 X$ \  D8 ~! C    // list from timestep to timestep
        
9 P4 C, I& J  m  y" G$ F    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
6 t2 h& p8 ?. @( I, V* D    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
6 b- U2 U. J* z, N! h3 Y/ t; c   
    modelActions = new ActionGroupImpl (getZone ());
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6 W+ [9 x; M+ X3 Z0 q0 p+ V    try {
      modelActions.createActionTo$message
2 o- x/ e5 ]8 G! K& v$ K- _7 C' ~        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
9 ^& T: X0 Y" E- E7 L& l& F+ `  I      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
" ]- b- l4 f) |9 E5 t      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
3 R1 L0 y1 N  B         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
3 Y- K) E( L' ^  o    } catch (Exception e) {
  G+ i5 q: k' d. d, i" ^5 }2 n3 F      e.printStackTrace (System.err);
) s/ Q$ H( Z; v* t9 j; Q: }4 {    }
1 ]) B2 i+ y% u% L* F& }   
, {4 P3 {& x. m- q    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
2 j' e% |: y" j3 g9 L    }
0 M9 C; M& C4 i$ T- U3 w        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
, Q) Q  G* D% J2 R2 l    // 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
    // just repeated every time. See jmousetrap for more
+ Z0 e& d9 l/ g! s! L    // complicated schedules.
  x' f: M! W6 P  
) A4 h1 }3 P5 l4 L    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
; j+ r- V! Q# `: L1 B2 S+ V4 |& x  }