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：
3 L% z6 Y1 j( u: A8 Q7 S
1 u( T7 x7 i) _( i public Object buildActions () {
    super.buildActions();
   
) j/ |5 x% G& s: G, p( I, V    // 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
    // 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
    // diffusion, then run "updateWorld" to actually enact the
2 [- T& `$ [; J) m    // changes the heatbugs have made. The ordering here is
    // significant!
4 K* R2 k2 U* q# V        
2 Z: o0 H3 j6 P* c    // Note also, that with the additional
& C- ~2 H1 R: y. j/ _* ~5 S% a    // `randomizeHeatbugUpdateOrder' Boolean flag we can
- c! m& b3 V6 v+ J7 b    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
2 C9 K1 |" z/ C2 _    // 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
- P: W9 A7 }8 p/ f* H3 G# o0 P* n7 j    // identical (assuming the list order is not changed
! Q3 e" v! ^" Y4 c2 U    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

9 N, K- n0 W0 ~    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
! _' w- O+ v" o2 B; W9 ^& U      System.err.println ("Exception stepRule: " + e.getMessage ());
) e4 h1 @$ ?6 n4 h  J5 d) ?    }
5 }$ _9 ^' G5 L
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
. u% K# l* G8 K9 v' M        new Selector (proto.getClass (), "heatbugStep", false);
( C. h* `. ~8 ?  D& q9 ?* `) m      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
3 h4 d% j. e- Z1 T. {2 V" Q                        new FArgumentsImpl (this, sel)));
4 r+ d0 i9 o) A    } catch (Exception e) {
      e.printStackTrace (System.err);
% A# d( @. v  ~+ O) F% ~9 b    }
6 ~0 A2 D2 V7 H: j/ k* ^, W; L; ?   
, n7 H$ J( b" O- b* X* e    syncUpdateOrder ();

    try {
7 @$ _+ a, A2 x' V, _      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
; w2 k( a1 Q8 T8 j( h2 c    }
5 e  T9 q  x; `) F( u        
    // Then we create a schedule that executes the
/ \6 ^1 o; a/ n. a4 w8 `. l    // 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
& z+ t% }  O. N9 W% K: H    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
4 E6 f. p  N2 l    // time step.  The action is executed at time 0 relative to
( ~* W2 \& u& l  Y# {4 f    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
2 H0 @* H3 q# Y    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
6 ^( U9 l, \% l        
    return this;
4 Q) p) y8 Z. k1 K  }