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：
) \2 K0 M7 Q) w! b" R6 G( W
public Object buildActions () {
    super.buildActions();
3 ?/ f: I  i6 M. w$ R   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
+ ]+ j9 Z9 X7 y6 g- u6 A0 Y# e$ ^    // executed in a specific order, but these steps should
' L! }, q- F( {- F8 r% A    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
+ y7 c- U! H6 ]2 G/ Z    // Note we update the heatspace in two phases: first run
" v; X: F8 h% [    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
2 k# c' [& j2 ^, I3 W8 V# ?    // significant!
& q% }6 t7 H* i3 e# F7 B        
' w) _7 @* z# b1 r  q    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
7 K6 u" ?* r4 c% Q    // 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
    // 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
# e, r2 O- w5 J' ^    // indirectly by some other process).
5 x4 a6 m: a! g! m6 j4 |8 f& ?   
1 U, S: V/ i  }; r/ d% b! k: P    modelActions = new ActionGroupImpl (getZone ());

! G6 L. H* i9 C3 c    try {
% C! y0 o) a+ _% u      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
" ?: P/ I1 ]- m$ ]5 ]$ }    } catch (Exception e) {
) ]+ G+ ~! V3 p1 [3 G- L      System.err.println ("Exception stepRule: " + e.getMessage ());
- m* G3 o0 A# a- m    }

+ P1 r& }% [$ I6 B$ a: V2 `2 J7 x    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
. U: ~8 b9 w8 X* N2 X( l        new Selector (proto.getClass (), "heatbugStep", false);
0 s$ N: g$ M% I+ l, F8 p      actionForEach =
! |$ S+ ^6 r- V  H  H+ h        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
6 H( h. D+ f7 D4 X8 k/ u  L    } catch (Exception e) {
0 ^* M/ q6 y7 U' z      e.printStackTrace (System.err);
    }
1 x4 @- f7 ~& ~4 ~+ K0 y   
% g9 q5 f) b2 S. n0 y! `9 Q2 V    syncUpdateOrder ();

    try {
( y: n  Y6 ?; P( u. ?* J      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
, ?* h; K* Z) i* d    // Then we create a schedule that executes the
1 U- R* J, R7 @0 u, l: T! }# I    // modelActions. modelActions is an ActionGroup, by itself it
. t. P  a% J+ D0 Q! V/ M& v$ M) }    // has no notion of time. In order to have it executed in
3 O! K. l7 S0 B  m! \0 h/ A    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
4 u4 }: U9 t; f6 P+ \) o    // schedule has a repeat interval of 1, it will loop every
* o1 i6 e. U- c. j# q8 b' T    // time step.  The action is executed at time 0 relative to
% j0 k& q; @/ W! Y; a    // the beginning of the loop.

2 n% l! Q4 b2 P) g    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
2 E8 F( l$ t0 H/ M8 y9 e6 ]% u7 _    // complicated schedules.
+ Y5 M" R7 B' D0 n1 ^1 a; |7 G4 |  
    modelSchedule = new ScheduleImpl (getZone (), 1);
  ]: a4 t' D  m! u& @5 u4 Z    modelSchedule.at$createAction (0, modelActions);
        
% K* L5 l2 F+ |  S9 [- \* u    return this;
6 r8 W7 E' T" B) s; ^% R' _+ ?) o  }