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：
7 E7 ~' u. M! P# k! }
public Object buildActions () {
    super.buildActions();
) }! U( l4 s" M# V   
    // 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
6 }/ C& f4 e; k6 Z    // 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.
+ F; A- S8 `; [5 s* [: o        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
. |6 Y8 D6 b- B6 k6 @( z! p9 |    // changes the heatbugs have made. The ordering here is
    // significant!
6 W# T: P5 d# ?$ ~. @7 H0 a        
; B, l. G, V% a# Y    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
* r) X! [! W" x/ v: B1 x    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
4 J8 v! K$ l  \  ~" _# \        
  d1 _3 _6 g. L) @+ W: F/ U    // By default, all `createActionForEach' modelActions have
, @- l& R( s+ v1 |% Y8 g    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
7 d  X2 v% N6 r2 D" U5 k; ]) j# A    // identical (assuming the list order is not changed
    // indirectly by some other process).
/ e! v" A$ b3 p6 `' v- R' ~5 O" {   
2 T/ ~  t. O/ G    modelActions = new ActionGroupImpl (getZone ());

, Q+ ^2 t9 `& y& n) a0 p3 b' n  E    try {
      modelActions.createActionTo$message
9 i& F) W/ q, o( ?* T' h9 f+ i        (heat, new Selector (heat.getClass (), "stepRule", false));
& t" w# ^) b. B1 c: N9 i    } catch (Exception e) {
7 P# T" h5 X4 o! F      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

) J0 z5 _4 L5 i. f) S4 y    try {
: S- @# {$ |4 f" T' O      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
0 L! D- B5 B  [. A      actionForEach =
) ^- v: o+ n+ l        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
8 J( |9 n% _9 Y6 _8 K; _8 @' K+ N1 X         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
+ m9 R4 Y, u8 s% T      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
% w5 O2 k# U/ M5 O3 K
$ c+ E% l6 j$ d" n' ]    try {
8 T8 f5 `4 z) y" \* t      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 P2 V5 Q" k$ i' w8 O: V! M    } catch (Exception e) {
/ w/ l7 ~" W1 F      System.err.println("Exception updateLattice: " + e.getMessage ());
: D* h+ s; U& ]. q* t    }
        
) L( I# ?. g! x* }# W    // 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
    // modelActions ActionGroup at particular times.  This
8 A* B) k5 [: L* ]    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
7 [: w/ b  h, `* e    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
3 A. a* P+ f& U. f    // just repeated every time. See jmousetrap for more
% s+ I# k3 i( k! S' {( `    // complicated schedules.
5 {2 H# }, [7 E0 l1 z2 @. Z: a  
1 i8 s6 G4 k( M% x( W% ]- [! c8 P' ?    modelSchedule = new ScheduleImpl (getZone (), 1);
3 Z3 s6 L' o0 _9 b; c9 Y" [1 u    modelSchedule.at$createAction (0, modelActions);
        
    return this;
5 J( U- {4 b* n! V; e  f7 C  }