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：
) U- k; W% m8 X/ A2 z3 y; `5 j, S  }
public Object buildActions () {
    super.buildActions();
   
! d1 d  a1 Z/ z: j" R4 y1 z9 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
0 \4 P; r! N/ I    // 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.
" r* m0 m9 t! O        
    // 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
  X3 |+ i. V  |3 g$ w6 Q( ~% h6 g    // significant!
8 v1 f) ~$ Y9 Y2 t        
1 d5 u9 ^2 O  o7 G( r6 K    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
- \6 g$ Z. X4 L0 v( L2 U    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
8 G) E( I: _2 c- S3 ~        
- e# h) N8 \/ E5 t# I4 J! _) H/ A! G    // 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
! ^- k7 ?3 x+ _: I* c( Z/ P4 H; y& M0 A    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

" |' j- S7 w' N# C    try {
% l" Y" x8 I7 Y0 q7 F) v0 C3 N      modelActions.createActionTo$message
: z1 v3 P8 e" O/ R2 ^        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
' A! q& V! _& S    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
0 F9 L% t; y; x5 {1 o        new Selector (proto.getClass (), "heatbugStep", false);
4 A) q/ U/ K7 E8 p  _      actionForEach =
  O7 B* q9 }  D! z6 Y" u        modelActions.createFActionForEachHomogeneous$call
8 x$ b- C# J, V4 n; S2 i        (heatbugList,
# }8 @4 f. |, `7 [" W! f. |# {         new FCallImpl (this, proto, sel,
2 j6 k" O, C! v0 c                        new FArgumentsImpl (this, sel)));
1 t) P0 b1 M& w0 Y    } catch (Exception e) {
3 v$ @; q! t" {: u6 X: [      e.printStackTrace (System.err);
/ P, U7 E1 _9 }    }
   
  ?3 ^9 m+ P( f- ~6 P. R    syncUpdateOrder ();
# t& [$ C! ^) G2 K! O" e
8 b2 _  s; G" \; I# L    try {
      modelActions.createActionTo$message
/ k) H( \9 D% y, m6 E9 h" @        (heat, new Selector (heat.getClass (), "updateLattice", false));
% O! _" s  f5 N/ F    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
, S! [/ x; J  N    }
+ m! v/ G$ Z1 V2 W) Y9 Y# Y        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
* T, F: }2 @% M! s2 \# L3 x    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
9 K* z6 w: @8 _1 o+ z    // modelActions ActionGroup at particular times.  This
1 i/ h. L: r# V# f0 s4 J8 u    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
$ E; a5 j* y$ O2 A3 s( t    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
' s$ S3 n# Q6 J    modelSchedule = new ScheduleImpl (getZone (), 1);
5 y9 L9 k4 b+ `) e" k5 X; f, p: s. j    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }