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：
" `/ a; s' q" a
. w: l2 t: h9 i8 z8 S( X public Object buildActions () {
0 S6 T' b7 m! m    super.buildActions();
$ }: r: h% ]' `' |   
    // Create the list of simulation actions. We put these in
  O1 p8 \+ _1 p0 Y! j# b    // an action group, because we want these actions to be
% T" y3 `! w9 V: y, z    // executed in a specific order, but these steps should
6 S- q' o! m4 `    // take no (simulated) time. The M(foo) means "The message
' O' ?: k6 k! f5 R    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
+ D5 _' G* X/ G    // diffusion, then run "updateWorld" to actually enact the
; }- T; O+ C) R% f4 v    // changes the heatbugs have made. The ordering here is
    // significant!
( x5 p  @, ?" W7 }9 M        
$ b; u. I+ [! r) ~! D6 H) \    // Note also, that with the additional
: N3 U1 t" h: z  r" f% c    // `randomizeHeatbugUpdateOrder' Boolean flag we can
, H  }; F/ g9 T, n4 K' C    // randomize the order in which the bugs actually run
& j; m& p& ~1 A" t& R. V    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
; v6 v: z, X$ ~& F1 A1 H) i) W    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
1 n- M( M( q: C, M1 r    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
/ v- Z; ^  o2 h; h. e9 T7 |# S  Q    modelActions = new ActionGroupImpl (getZone ());

2 A& i8 r# C+ [& V    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
2 n( N3 y9 o, H& U; ^    }

9 o! E% t, M: z8 t$ Z  O- A    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
. F1 v7 ]  @* |7 V3 \; @      Selector sel =
: z, X: p4 v- a        new Selector (proto.getClass (), "heatbugStep", false);
0 q4 ]) S( v; a- p# E/ s/ d      actionForEach =
' T* F* q9 E$ V2 J) u        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
) n# ?- H4 a4 h! U, o    } catch (Exception e) {
9 c) m; S  X" B      e.printStackTrace (System.err);
    }
   
5 _4 w' H- N" I6 ^+ e0 ~    syncUpdateOrder ();

    try {
6 \. T9 S  f  t& K" X1 l      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
& |5 W. l( l+ }$ K5 d2 G, ]- ?) h3 l( ?      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
3 M1 j4 b! \3 M% j+ @        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
" Z/ t# N& j+ R7 q    // has no notion of time. In order to have it executed in
1 v% x2 j. h7 d3 ?+ J    // time, we create a Schedule that says to use the
8 K  ~/ A# ^  @) ^    // modelActions ActionGroup at particular times.  This
. w% M1 C  a9 E( V5 \' r  \; ]3 f% t    // 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.
& }: a! r( M* M" F. O
    // This is a simple schedule, with only one action that is
- W2 }" I* a4 ^$ \! ]% q% \# V2 H    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
3 Q0 \/ o+ d" y8 G# X' G8 m6 C    modelSchedule.at$createAction (0, modelActions);
        
/ s# p8 e  B* F; F; S8 ^% F* m  k    return this;
' ~2 b* v9 f7 V" p: U  }