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：

+ }+ i: q2 Y" B1 p/ P public Object buildActions () {
- G$ v8 G. R1 {2 y    super.buildActions();
   
    // Create the list of simulation actions. We put these in
, k* J) J) f' p6 B    // 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
: L9 Q0 C! x: u7 a    // called <foo>". You can send a message To a particular
2 A4 g" B) G& ^! d    // 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
6 _, k5 Z- @  I5 G    // changes the heatbugs have made. The ordering here is
    // significant!
        
; p/ ?: U0 l! N' ^  {- b' t; B    // Note also, that with the additional
+ U# s. l4 o0 T$ G9 k$ x    // `randomizeHeatbugUpdateOrder' Boolean flag we can
, V' N$ W, Z& X$ A, R4 K/ A5 m8 z    // randomize the order in which the bugs actually run
! d+ p3 o) C4 }: p1 N, X; E    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
. a3 X* P- J/ G0 l4 g% p    // list from timestep to timestep
# ?: K: r" {6 d& L' Q0 k/ Y" C        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
" ~; b% }7 D% I    // order of iteration through the `heatbugList' will be
7 ]  O1 Q  L: ]    // identical (assuming the list order is not changed
    // indirectly by some other process).
+ o0 E  r* |* c7 B7 H- l   
    modelActions = new ActionGroupImpl (getZone ());
* B/ V* ]( g+ U3 i# a
    try {
      modelActions.createActionTo$message
  ~! F* C! U  ^5 n& J) a        (heat, new Selector (heat.getClass (), "stepRule", false));
: Y: m1 T; V/ Y# p    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
) Q' f& s" O5 [6 K# Z        new Selector (proto.getClass (), "heatbugStep", false);
, h+ x4 a" k, ~# y. W( K  z8 ]- R      actionForEach =
% a5 N7 V* R8 Z6 L8 s+ T! X7 \( U        modelActions.createFActionForEachHomogeneous$call
/ j8 h# I6 i. R4 ^, I/ e        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
- t6 t" A/ E. A: Z' X    }
6 X4 t$ R& L. e* O# T0 ^/ ?. P   
6 j& Y! a, s0 w2 l0 X    syncUpdateOrder ();

    try {
9 N! `% p7 G+ n+ w; f      modelActions.createActionTo$message
9 [* r% ^) X& a- t' O) V# a8 b9 ?        (heat, new Selector (heat.getClass (), "updateLattice", false));
& B5 i; I3 E& a, J8 q    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
3 c, d0 [7 H, w7 Y/ L    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
% B6 [4 B0 Z/ N" T. j/ w    // 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.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
6 _+ i! Z8 Z9 `2 q  
" n; Q5 }. y  P+ N' G' ~* y/ M3 ?    modelSchedule = new ScheduleImpl (getZone (), 1);
. L) k- ]+ \" k5 k3 Y    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }