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：

( \  }; T+ @3 Z, c5 P) i public Object buildActions () {
    super.buildActions();
' i* @# @5 _( X( H   
# l5 u2 [) ~5 @* o2 ?    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
& x% [9 _1 }% U2 s) Q3 w; Y    // executed in a specific order, but these steps should
, D' v, G/ |, K2 Z/ t    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
+ k- d' ]# r" U2 \/ a4 O    // object, or ForEach object in a collection.
$ i5 H3 K. `2 o$ O( m1 ]* a8 F        
    // 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
% H) j% w0 L, ]2 y    // significant!
        
+ l# N. Z; a+ d    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
    // list from timestep to timestep
        
0 y8 d5 Z4 k4 T8 e7 {    // By default, all `createActionForEach' modelActions have
. Q: z4 O* b0 y8 Z    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
: M* y' i! d% a6 J+ h, W. }    // identical (assuming the list order is not changed
" P0 C6 P% F* H    // indirectly by some other process).
  v; r  v  u; x   
  B8 s# |, }8 Q: L# E    modelActions = new ActionGroupImpl (getZone ());
' m8 Q5 ]( _! [( ]8 s
; _' |9 b3 l- ~) p4 m9 U    try {
      modelActions.createActionTo$message
+ s( S1 ?' K2 u+ i$ D        (heat, new Selector (heat.getClass (), "stepRule", false));
" H3 f: D+ g* q8 h    } catch (Exception e) {
1 Z8 W8 q& g* J      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

) X* g+ A) T9 k% {6 L% }2 {4 a    try {
) `0 l' ]2 r9 [/ |$ M2 y      Heatbug proto = (Heatbug) heatbugList.get (0);
6 F; c/ i0 R) j4 I0 Z  s) R      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
* J* z/ A& B! t9 F  ?3 _! E) o      actionForEach =
" e1 q, e5 ]' @8 l/ @! }" Y        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
5 Y- [% y' L8 h# u; t      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

1 A$ {# f1 F7 ]- N2 s: N, d5 C    try {
) t/ L* q$ A) \      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
. h( w6 j  H) u0 V# R    } catch (Exception e) {
) g. w. h, Q( h4 ], M      System.err.println("Exception updateLattice: " + e.getMessage ());
4 S$ e0 M) Z9 L) I. j! a    }
        
    // 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
/ K4 r2 O4 z! e# V3 o/ B    // 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.

+ }/ x5 J1 _5 M& r  t! k  v    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
4 K- S; @* A9 j- G( J) m    // complicated schedules.
  p) O  e8 I* Q  
7 i: l% E6 H2 H" i3 T* O5 ^    modelSchedule = new ScheduleImpl (getZone (), 1);
4 C: r% ]9 J/ o! `    modelSchedule.at$createAction (0, modelActions);
        
1 O& t% }9 O; G+ R# v7 U* W    return this;
% @$ _) |; D. X7 n* N  }