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：
* @+ j! s2 o2 A/ M" L7 z& a. \& }
public Object buildActions () {
    super.buildActions();
# b8 c0 @: a( p! ?   
    // 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
" s: @% r1 l& `$ x    // object, or ForEach object in a collection.
! o, W7 k- M  [/ V/ O        
) X7 Z; }) R( X) j& o; ~+ Q    // Note we update the heatspace in two phases: first run
  K( v# m+ E' n1 L8 V3 O6 ^    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
( @+ Y* }6 C. G8 t. r% m& @        
    // Note also, that with the additional
, q) s3 w. q; y  j6 _    // `randomizeHeatbugUpdateOrder' Boolean flag we can
# J" T% D7 c% F0 ]. M5 G    // randomize the order in which the bugs actually run
# ~# l4 p# J% Q! ^    // their step rule.  This has the effect of removing any
4 [# y6 a1 E- D, |/ W" Z    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
/ n1 Q& l! a! K+ w$ v    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
! v! P. S1 r9 o* ]    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
( P' B' ]2 ], U) t+ V- Z- g   
2 U2 Y. L- i1 K# h+ X8 V& T9 U    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
. w6 q8 E5 |- W        (heat, new Selector (heat.getClass (), "stepRule", false));
% y4 h/ K  V; V- ]' }: C1 i5 r    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
" m! O1 V* a6 w( x    }
& r& n. w  D) f, J
    try {
( k* ?# P6 Q! v" o2 _. P8 p8 I) k      Heatbug proto = (Heatbug) heatbugList.get (0);
6 a6 k3 O" A4 s% c      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
9 p9 q$ P. X3 {$ }4 ~" U5 f& j      actionForEach =
+ |8 e2 f2 C( u        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
; Z, ]4 ~3 R& O         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
* [% Y# u$ B# C2 @7 U% X# B    }
   
( A$ f# t" Y6 b4 G3 _# ?. ^# N6 Q, v  d    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
. e3 l# P- k2 Q1 t9 U0 L; ~8 k5 d) _    } catch (Exception e) {
* H* z9 f" s2 v4 N1 [: j      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
2 s2 J1 J; z0 q0 I) Z# E" W' 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
; Z, @) R  x5 Y! u8 ~' r$ X    // schedule has a repeat interval of 1, it will loop every
- b  [! N" W+ X: r8 q    // time step.  The action is executed at time 0 relative to
6 ]' O! [: `3 G0 J    // the beginning of the loop.
% E, \' P& x  I  K7 I
' U! u8 L" Q5 e) L0 x    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
  ?/ t0 ~2 s2 P, [6 j0 r        
    return this;
: a/ P6 m4 j8 K: L( f  }