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：
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) L2 [" P: u2 m/ ^1 b, O# p public Object buildActions () {
# G$ Q7 m) f0 v) N9 d    super.buildActions();
   
/ P6 `. [. \* q$ Z% d8 L    // 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
    // take no (simulated) time. The M(foo) means "The message
9 d5 y) E( k8 P: T, f5 @% l0 T2 Y    // 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
    // diffusion, then run "updateWorld" to actually enact the
$ [/ b! c) h, T% ?% |% y7 q    // changes the heatbugs have made. The ordering here is
: `) H: M" ]3 Z    // significant!
        
$ D: i) V# ^% h1 H    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
) ?0 s2 m0 r1 N. Q# P+ S* q    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
. Y- g6 v* ?5 r+ k    // By default, all `createActionForEach' modelActions have
7 s+ y. N0 {2 ~- z" f& n3 c    // a default order of `Sequential', which means that the
) o4 z0 |" {9 @    // order of iteration through the `heatbugList' will be
* r1 L- i+ M8 A8 n) I# O, i    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
: s2 N6 M0 y/ ~# }: a+ \      System.err.println ("Exception stepRule: " + e.getMessage ());
' K& x" S4 G- B3 F6 L/ r" U    }
3 W$ ?- \9 w8 r' x3 n7 S( X* y  {
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
" L; j/ b9 P8 `" e; N8 c8 r0 W2 O        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
1 D' F" u5 C/ m% W' \        modelActions.createFActionForEachHomogeneous$call
5 G! R2 ]! G9 e/ H; i        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
) l& `7 O. G8 T( q$ D    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
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& n6 x% \" W( O8 F% K    syncUpdateOrder ();
8 o5 K% F% y0 C& U5 F
+ G0 i! d6 W* M/ q8 v& j' W    try {
      modelActions.createActionTo$message
3 y& ]5 n, x) V, y0 W  O1 M        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
( `8 L' b1 y; e" S7 l        
    // Then we create a schedule that executes the
2 E; J& a4 I$ {+ H    // 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
0 f& F* q+ H" Y; U" }, r    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
+ n2 N: }( Y# \    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
& B' U* `5 A# ^/ [5 U' j* Y    // just repeated every time. See jmousetrap for more
3 u3 p/ w, i: s    // complicated schedules.
6 q" Z& O) [4 Z9 w8 v  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
) i# b9 C. M( r$ d  j$ z8 Y' U$ |% v. F  e        
( U6 m7 Y+ K3 T% S    return this;
  }