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：
. D3 E0 }# E0 R; V# [
public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // 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
    // called <foo>". You can send a message To a particular
5 Q1 U+ {& J+ r  l7 I% e    // object, or ForEach object in a collection.
        
! e4 H9 \# C- N1 X2 A# m1 _) N    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
: X1 _( v$ h' I: b: o8 B    // changes the heatbugs have made. The ordering here is
    // significant!
& z- X8 b0 Q) J* {0 h: A        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
  [/ N6 J. S% b& t2 Y* W3 t    // randomize the order in which the bugs actually run
# ~9 N  L; i+ a# t" a8 E+ ]: K1 I    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
& s, i5 z  E4 A0 j. }/ @: F- ^3 R        
    // By default, all `createActionForEach' modelActions have
" u, v2 _* ]8 [3 @% @$ z# n# e    // 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).
' I. o. @% W1 L6 n" }" i   
: R% {6 g& Y0 g  u    modelActions = new ActionGroupImpl (getZone ());
! X0 ~: d1 K+ z: e8 ~
, ^+ H, Q+ V2 b    try {
& P1 }/ M2 ?$ g      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
" T3 V- r5 E/ \# b3 [9 g    }
2 z! N4 T/ ~: n0 ~
" c% [7 Q( o+ @% M" H+ Z; C# P    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
' {7 x5 x- {3 T/ V- }% i4 T4 S/ ?7 ^/ b        modelActions.createFActionForEachHomogeneous$call
) ?+ {+ l% B* P/ k+ U: D" W/ k, i  |4 r        (heatbugList,
" t8 n) q1 F: }5 |: ]8 T, ]  Q# U* g. {" T         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
# s) M2 u. }. V: ?* Y0 o
    try {
      modelActions.createActionTo$message
0 k" j. `/ I3 U7 l! ]7 M        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 q# i9 t/ O  @, L7 H    } catch (Exception e) {
  {. N6 u' ]9 f& `9 n      System.err.println("Exception updateLattice: " + e.getMessage ());
. I8 l0 P) a2 Q# o    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
$ U, X9 @. R' q- o6 }' t+ C    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
4 j$ K" E& c4 v$ o8 V. [+ \    // schedule has a repeat interval of 1, it will loop every
6 q0 J% ]2 t$ h5 ~    // time step.  The action is executed at time 0 relative to
* B. Z4 h! Y& l% M$ ^    // the beginning of the loop.

* L5 |7 I9 X) G6 Q* s. m    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
$ \& G# R/ }: p" O+ [7 I    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
' s2 A. v1 f3 w6 O9 T* P% y3 _        
    return this;
# K# k- v6 R9 g% j  }