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：
- m: l( S2 u2 q# K6 N5 ~
2 G% O: |; S( b; \/ V5 A7 @ public Object buildActions () {
, e0 o" C( H! Q: b" M5 `6 w: K; u    super.buildActions();
   
* k+ U/ g3 X2 N    // Create the list of simulation actions. We put these in
# r! D  h! h' z# ~. h# j    // 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
1 H+ [6 j! h. E    // called <foo>". You can send a message To a particular
' C1 v2 v2 \! j2 F    // 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
    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
$ O  _6 `) I- p, J5 q5 O% V" Y2 ^0 w# F1 t    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
& B8 T. l5 {* z8 P    // their step rule.  This has the effect of removing any
+ m; r9 t2 @$ c9 r' Q    // systematic bias in the iteration throught the heatbug
4 p7 i/ ]" @" M    // list from timestep to timestep
        
9 R6 a6 _: a9 Q/ S/ \; n+ {# \3 I    // By default, all `createActionForEach' modelActions have
    // 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
    // indirectly by some other process).
/ L. L/ o% P. H  m, D+ L+ g6 }1 \% J   
    modelActions = new ActionGroupImpl (getZone ());
1 R- P7 g+ w, O% c/ T
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
5 q) o7 ~) F  w2 P  n* X. X    } catch (Exception e) {
6 }) k6 e9 c! J' t7 K$ Q3 U# m      System.err.println ("Exception stepRule: " + e.getMessage ());
( G$ ~2 k# ~. D9 P1 y1 w* V+ X  J* E9 r    }

+ \  x  ]) }% t1 R2 M+ T/ Z2 |3 E' A0 \/ B    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
) M$ C6 V+ s. E) S        modelActions.createFActionForEachHomogeneous$call
/ |/ B0 F! V' @: Q$ u        (heatbugList,
. A7 F1 b% g& ~$ |         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
- z; M: [: C2 O    } catch (Exception e) {
      e.printStackTrace (System.err);
6 i% U' h4 [0 s- H7 F    }
   
. R( r0 ]6 g. S. {( T" Z    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
6 g/ H5 x8 m' u4 I    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
- @1 v3 d) S5 L' Q9 q    // Then we create a schedule that executes the
- R7 M# {% t- E/ ^- n+ C9 l& M    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
% P0 y5 v, o7 p- n+ T) B% |5 d; C    // time, we create a Schedule that says to use the
; ]# @1 a/ u) k$ ~0 Z    // 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
* A+ s" J. j; |' Z( p) `& J8 x0 l    // just repeated every time. See jmousetrap for more
1 _7 `4 H0 g" t, Y% ]% e; g    // complicated schedules.
; @6 q! J0 t3 @5 O  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
6 }+ q2 L. z+ z. N$ V1 t' U        
    return this;
  }