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：
/ r. S5 ?6 f, J, q# e" @" w
+ o7 m7 e6 Z8 c3 u$ L public Object buildActions () {
    super.buildActions();
' K* n3 H% B1 Z   
; J. [- m* C8 N& h# T& Q% w$ s7 Q    // Create the list of simulation actions. We put these in
8 y0 [4 {7 ]& g( `6 {    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
+ j  H, P+ E6 |) K1 L    // 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.
5 w" ^; g8 L: [+ P* v        
+ }. Y$ O* _' J- O! o# V    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
/ W5 V# r+ q2 _/ \1 A( O    // changes the heatbugs have made. The ordering here is
/ v. P  a$ l3 E" r    // significant!
4 ]( J& M6 S$ s& i! o5 }- y        
# F! s0 c$ \4 c' W! Z! \    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
4 P7 o- W* K$ R/ Y0 E( U; s    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
5 p8 h# T7 |: s0 ~2 m, p    // list from timestep to timestep
( j  k& z: h6 a1 @/ v5 c) O        
3 t8 r' H5 V1 o5 |    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
* e! q9 e: d+ m4 Q: C1 t7 C    // identical (assuming the list order is not changed
/ L! n' _' q. }7 |7 z4 G    // indirectly by some other process).
8 l/ x% I7 @4 G; d5 z7 J& d' i   
( v& D& `3 O' Z    modelActions = new ActionGroupImpl (getZone ());

( G& }: J* C4 R, O    try {
  d! `" z# k  U$ m* b      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
3 ~: r' _# k$ U  t; O0 p        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
0 X: l; N, I: z! X1 }0 J8 v" ^/ F* \        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
! G  W, t) z( a% K/ S) i- }    } catch (Exception e) {
      e.printStackTrace (System.err);
( z- t% _6 v2 Z% C& [  m    }
2 D8 ]; A+ J. J6 B4 h4 r5 V   
  o* u7 r5 }# F; I. K    syncUpdateOrder ();
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    try {
& h6 u8 f1 V& ^4 m      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
% Y# s0 J& b9 h    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
+ r# o) h) V$ |' J( Z/ m: R    }
& p( Y) ?& j1 Q8 B        
9 C9 N* V: m) d+ J% u1 j1 t    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
: m" k5 C, Q  O1 N; _  ]    // has no notion of time. In order to have it executed in
6 a1 s% _3 N$ C9 y% k$ d    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
3 B1 g5 l5 e5 ]* i7 }! s1 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.

    // This is a simple schedule, with only one action that is
: ^+ e: E; H: ~    // just repeated every time. See jmousetrap for more
    // complicated schedules.
$ Q: n9 L3 m$ {  
2 Q4 W: R7 b. j% Z! V- }- i5 j    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
% u* F9 ]( S/ L7 S, Y9 ~        
+ F! `) \7 I# C* g) @2 ]    return this;
  }