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：
# X& @; n1 W9 P% B2 u4 x$ b
public Object buildActions () {
    super.buildActions();
   
* A0 P8 _9 S6 f7 R- ^9 T    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
' P! r! ?; H- e: M: ^, l% I6 j    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
- e7 J& s! N3 U7 a+ F, i    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
( V, @0 V% x; }# m" f    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
+ Z$ S; i) }" Y# L2 T2 B7 }4 ?    // changes the heatbugs have made. The ordering here is
1 P: l; @3 e2 l1 f" O" ?    // significant!
1 [% P: G* G5 f% h: |        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
+ Q; R) D0 W. X) r8 f* e$ |    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
9 Q8 U1 n& |9 k' L% n    // systematic bias in the iteration throught the heatbug
9 w4 Q% n( u1 {# C    // list from timestep to timestep
        
) A/ E* O- g+ u! j8 {0 d! d$ [    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
) p; m0 i$ g3 `7 Q    // identical (assuming the list order is not changed
    // indirectly by some other process).
" N' h8 x: |! J( T  `6 N4 t   
    modelActions = new ActionGroupImpl (getZone ());

. _9 w  j' n0 K    try {
! B2 q; D3 e$ \% }$ Y" v3 X6 ^      modelActions.createActionTo$message
' s: {4 _* v, S/ J: [        (heat, new Selector (heat.getClass (), "stepRule", false));
: n! ^6 h; q/ |& V+ n    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

% H8 E, L4 [& t) x, R    try {
: {/ U4 ~% M) ~7 D      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
; P3 i3 K/ ], m        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
, j+ @! Z0 n! O9 c; v) ^, o0 s                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
1 p! i) @4 ^7 k% ~/ l      e.printStackTrace (System.err);
! r) V6 H7 ^8 ^, d    }
# Z5 Z$ V0 u: Q" b   
    syncUpdateOrder ();

9 h2 F+ L2 u% X( a    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
) x  X" b  }$ _6 d! t, N; |    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
9 W6 ]$ M3 j: w6 Q9 A& ~7 S    }
        
9 Q- e+ Z0 g, l; p' w# o8 H' O    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
6 a# d& I! K- I2 X% Q    // 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
: J2 Q4 q' @/ D    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
) P$ K2 C7 y2 M( I$ A5 t: a% F    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
! j& J* g* R! k# S4 T3 g* Y$ N    modelSchedule.at$createAction (0, modelActions);
9 ~4 g6 Q$ }( s/ X& J8 V        
    return this;
  }