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：
' ^  }- B0 ]- U/ }) j) v! E( s& `
! B$ q3 c$ j. L% H$ p4 i public Object buildActions () {
    super.buildActions();
: R$ a6 g) _4 ~2 V% G1 r   
/ G& @; ~- j* z% k. |    // Create the list of simulation actions. We put these in
9 ?* P. B# F2 g" V( X    // 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
7 W4 L/ n, G" V. T  N" B* B  M    // 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
; }# }4 Y) E" ?2 ^3 l( f0 M8 L    // diffusion, then run "updateWorld" to actually enact the
# ]1 y: F8 A) i2 K    // changes the heatbugs have made. The ordering here is
$ J& f# @6 ~* W    // significant!
1 Y9 O; }' a: b, u% d        
    // Note also, that with the additional
2 E1 g  e# o' B5 w    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
- o- B8 ~1 R0 w( \7 s; r* v    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
3 a! e0 W: b* T' d- `  p    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
  W5 q9 a  K/ |2 ^. K    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
. ~+ i5 t3 [# y: w9 h6 w% ]
    try {
      modelActions.createActionTo$message
2 y5 h$ w4 H$ I! r* H  z        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
2 H9 N* P/ v% K      System.err.println ("Exception stepRule: " + e.getMessage ());
6 {! l0 D, a" O: Q6 c. W# H/ n    }

: I6 c- H) E! s* s4 J    try {
3 t& P* k+ `6 h4 ?  u* c& T/ x9 u      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
9 s, e- N/ o* F; F" r& X* K        new Selector (proto.getClass (), "heatbugStep", false);
3 o6 y' G  I" M+ y2 G: R      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
! x- }  H# e& F+ u8 v    } catch (Exception e) {
      e.printStackTrace (System.err);
4 u. K3 H' [# y. t" F0 w    }
   
    syncUpdateOrder ();
0 F! f1 G3 u7 u& w. e6 B) u
    try {
      modelActions.createActionTo$message
3 {: w& z# j! k' [        (heat, new Selector (heat.getClass (), "updateLattice", false));
! q, s" w8 m% }* v1 z    } catch (Exception e) {
$ ]8 j1 r  k6 ^8 |, Y4 b6 g      System.err.println("Exception updateLattice: " + e.getMessage ());
$ a4 P1 V; n, n6 V% }    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
* g: ^- X( C7 a5 a3 Z    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
1 |  `7 F& D1 c9 S6 q+ b/ ^6 a. @    // 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
# o. r, ~  F- u8 g    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
! K$ k9 n8 S/ X- B* C& E- @/ c    // just repeated every time. See jmousetrap for more
3 Z* @+ g) R6 _; I6 D9 ^    // complicated schedules.
0 N) U/ S$ u: u  t  
3 E4 S) l: C, @    modelSchedule = new ScheduleImpl (getZone (), 1);
8 i& I% R: Y- t    modelSchedule.at$createAction (0, modelActions);
        
9 ~, K; m  `4 u* b- `# I+ V    return this;
  }