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：
% |* Q" L" y8 M4 a$ ?8 }
public Object buildActions () {
    super.buildActions();
: Y- ]* y: X4 [+ }: _; Q   
) c( P9 t0 K* O    // Create the list of simulation actions. We put these in
' r" j8 l1 k9 P    // 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
+ Q$ V$ \$ Y: L' K' l4 ~    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
) D& I  Z, b# l4 E        
7 c- I2 S) _- h" L; \# R    // Note we update the heatspace in two phases: first run
6 e  f' E2 Z5 A2 Z$ c! e2 Z    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
( E9 b% l. v7 ]! X        
    // Note also, that with the additional
% b9 }2 ]& o* G    // `randomizeHeatbugUpdateOrder' Boolean flag we can
) \5 n0 i- R& a6 U/ C    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
6 {- n9 D- k1 k1 N0 \3 |+ v; o9 b    // systematic bias in the iteration throught the heatbug
5 ]/ M# [1 N) v) D8 A5 H' U0 E2 T    // list from timestep to timestep
. h5 @4 c! R6 [9 B        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
+ E" Q) M8 m0 h- M4 p  t$ S    // identical (assuming the list order is not changed
  [& O& @# U6 S2 N5 Z    // indirectly by some other process).
; y' D) l& f0 t" {   
    modelActions = new ActionGroupImpl (getZone ());

( m& G$ x# p8 a* O- b    try {
      modelActions.createActionTo$message
2 ?0 R$ s# W' o0 G; a        (heat, new Selector (heat.getClass (), "stepRule", false));
; D: J0 y7 M$ L# H* Q1 Z! W- x    } catch (Exception e) {
  F1 E$ `: z% p8 C      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
, J0 Y% G& F4 E9 U# Z
    try {
7 L* u* ?/ r5 \4 W: |4 O, }  D      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
: ^% T. J' E* p+ w3 L* X# L+ G  U        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
- u% T7 k3 u* Z        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
- h5 W2 U: }  s" A5 @         new FCallImpl (this, proto, sel,
( \( i3 N. ]9 i1 H                        new FArgumentsImpl (this, sel)));
! @' l  Z8 Y7 H" d- D    } catch (Exception e) {
: V; B3 ?' C& T4 }1 h/ X; L7 j      e.printStackTrace (System.err);
    }
   
: Y' C: m4 n) V. h' h    syncUpdateOrder ();

( W' p' |8 W" ]4 ^, @9 J. j. a    try {
# \6 N) h/ Z) V      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
8 z% ?- N" a' k( P$ M& h3 y: l0 n    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
4 I1 ~! a; }: b: Z2 I. p% G    // modelActions. modelActions is an ActionGroup, by itself it
( T6 n) ?2 o" |    // has no notion of time. In order to have it executed in
" r$ U+ f6 O1 c1 I! e- H    // time, we create a Schedule that says to use the
0 q" D3 J/ w  H    // 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.
2 _* k, I8 I/ A. R0 x, W
/ w/ W# o1 H+ p5 `6 }1 l; k    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
3 {; q( v& m# G; q& s+ W    // complicated schedules.
, A6 |& U- ^* T8 f2 t) |  
    modelSchedule = new ScheduleImpl (getZone (), 1);
* k7 y# A, v' L  o    modelSchedule.at$createAction (0, modelActions);
% X! v& w+ Y  Z, L1 p6 m        
    return this;
  }