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：
: @# d: u% w) @; P& ~
9 ]& ^/ L9 ?' r public Object buildActions () {
    super.buildActions();
  C, R, _/ |7 M) m. s: g   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
: H/ g7 B% ]9 G3 n! }1 Q/ `    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
: L$ c# q% |: I6 `8 @    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
0 e% C& m1 r3 w! q! y$ I6 l        
# L" q9 X* c- t    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
* G; y3 n/ c' h8 a$ l    // changes the heatbugs have made. The ordering here is
* k6 E& ]0 r9 g, f( H    // significant!
        
8 a% [$ C/ U: V" K& B5 r1 l    // Note also, that with the additional
: f: y$ [" F0 l% s* B    // `randomizeHeatbugUpdateOrder' Boolean flag we can
# j8 {, T; Y; X6 }! j( ^/ A' f    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
. D5 q7 Y+ [3 R+ g# G3 m* e    // systematic bias in the iteration throught the heatbug
$ z7 [& g+ I+ ?, }* b/ Z2 Z; M    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
" x4 M" ]3 r8 X7 Q) b    // a default order of `Sequential', which means that the
) N( U+ F+ R( c+ c    // order of iteration through the `heatbugList' will be
3 ~. g4 c  N+ w* i! J    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

4 ]( r) j5 E! `- V* m6 P) v    try {
( n, M: |) t/ X% G8 ^) q' F      modelActions.createActionTo$message
3 B& U4 d5 |6 ~3 i        (heat, new Selector (heat.getClass (), "stepRule", false));
0 t3 K$ U5 T; I4 A7 `" k    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
2 {8 t9 v8 O% m9 t+ E9 f/ E8 K4 J      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
. J5 ]" E' S  X" V$ d" g      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
% v6 L7 g3 V) o0 Q7 r, ~        (heatbugList,
8 h: d+ f% r4 ?# w1 W- z; d+ m& M% B         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
6 v4 `0 }7 G: ^3 f; L    syncUpdateOrder ();
% ]6 ^/ p& T# C; X
% _! V& y  h$ a8 ]' \    try {
      modelActions.createActionTo$message
) S9 T+ c" e5 H' v        (heat, new Selector (heat.getClass (), "updateLattice", false));
/ H4 Q* K* f9 N4 N# A8 _    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
1 @8 U4 D# }) V# V, K+ i5 t! c  H- f    }
+ m2 @, }- C7 i" w) n$ r* x" M        
) n6 H, S) C+ s. [4 g, K    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
  M. o2 @) j2 ~7 b& r% k4 ?- ~    // 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
    // just repeated every time. See jmousetrap for more
6 o: o4 d" K% {( \4 o    // complicated schedules.
* S$ b* H; ^* Y9 y" j  
) e# r: g% ?6 g1 J1 s    modelSchedule = new ScheduleImpl (getZone (), 1);
" i0 f* U6 A. K" W7 M. ]    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }