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：
9 {, l) S/ G4 d/ W
( \! K$ p( @7 y6 i' a9 M% I1 A public Object buildActions () {
    super.buildActions();
  z0 `+ Z3 G) I* u, }   
" m1 l( V8 p  U& D4 ^1 y. l    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
8 d. `1 }. ]# T  y    // executed in a specific order, but these steps should
: ?. g! n5 q, i6 M) _0 C. N# L6 R    // take no (simulated) time. The M(foo) means "The message
0 B. X) c8 i$ [) b/ B/ I! u# {    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
" L, o( C- O( X1 }) \+ \2 `    // 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!
        
    // 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
- r6 B  v; m# R* G$ @    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
+ a6 J  ~: C! y9 e6 c! s8 O    // By default, all `createActionForEach' modelActions have
, c0 C$ }% q: u; h" Q; a/ [    // a default order of `Sequential', which means that the
+ @0 |$ T0 x/ t% \& t* R    // order of iteration through the `heatbugList' will be
: B3 W, Q) k3 F/ v    // identical (assuming the list order is not changed
    // indirectly by some other process).
% V& L( j3 {3 ~' K7 K' o   
! {8 z7 H8 C. I" U+ Q4 z    modelActions = new ActionGroupImpl (getZone ());

    try {
. A) y. s5 U! u2 S2 }      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
4 m4 F+ a0 f/ ^! o      System.err.println ("Exception stepRule: " + e.getMessage ());
6 F, P' r- J7 X. g3 E7 B: F    }
+ V% J' ?/ X0 {! k7 `
    try {
0 D$ M: }6 [, y) P5 t      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
3 V9 m* J0 z: Z" T6 c5 F/ P      actionForEach =
+ S9 I, ^" F$ U- _* b! Z/ ]$ O4 ]        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
: ~4 r: {% i$ @# w1 D                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
" o( `$ {& ?+ `; m: L      e.printStackTrace (System.err);
    }
   
$ A  s5 m+ c# i1 O: S6 g7 P    syncUpdateOrder ();
. b( w' `8 c, k
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
6 I. Z2 h& j4 F  H2 R% T6 }# I      System.err.println("Exception updateLattice: " + e.getMessage ());
! W# d# T  Z5 F+ a- P    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
6 _. T# t  p3 Y4 a- {    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
: r) `" W4 ^  g3 I2 D) t% }0 W    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
$ U3 y) q' U' `    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

& ^9 G; C" ~; Z8 H% |    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
5 h4 _; ?9 Z: ]4 i# \" e  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
' p! O# X! C) r  M. ?! ?3 F! C        
; R: Y1 a8 p1 X5 I0 F, o    return this;
* @2 ^$ i( [& n- ~* ~0 Z* ?# w  }