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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public Object buildActions () {
    super.buildActions();
) m" \; ?  z2 g2 m8 A6 w; }% _' X   
; R& S2 A/ _2 I    // Create the list of simulation actions. We put these in
; K3 @; P4 e$ a* q& Q9 d    // an action group, because we want these actions to be
. R8 x' C' W; X; l    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
9 v/ x9 y! C! s% ?3 _0 n- {    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
  e0 k; Z9 f1 h' r  B        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
) }- a- Z4 \, a+ m; b5 Y& j. C" E        
    // Note also, that with the additional
. A4 M5 C9 o" v3 a  j: |7 a    // `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 ]7 i2 l  l! P, _    // systematic bias in the iteration throught the heatbug
4 h6 d7 j1 n' K2 M( G5 c  g    // list from timestep to timestep
        
+ M5 j3 x& N( ~  N, Z    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
  h) H; k% I+ ~. S2 ^) C3 T" t6 |   
: k6 ~. V5 ?) W  Z; W% L3 z    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
5 x: p+ P7 t$ Z6 w6 w0 H. ?0 y    } catch (Exception e) {
6 F/ K5 u0 f; g( N4 l1 `- h7 L      System.err.println ("Exception stepRule: " + e.getMessage ());
2 c" V; w- z& W. ^    }
/ [4 N1 k# V  K& Y0 `
8 K# ^- o; m- I* h+ x$ p    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
$ W5 d# Z8 ]0 f0 A- @! Z8 }) D      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
* v, k3 N/ ~* a% r: y# q: |# f      actionForEach =
/ A4 R+ [3 K. t2 F% y+ d        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
8 I/ t+ Q8 l1 L         new FCallImpl (this, proto, sel,
1 O  Z- }2 ?& y% _$ c+ D                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
2 p; m; F8 y( m   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
3 K5 D' w; _. d/ `        (heat, new Selector (heat.getClass (), "updateLattice", false));
: T9 V/ b. J, ?, N/ `    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
: B7 L, Z  u' Z    }
        
    // 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
    // schedule has a repeat interval of 1, it will loop every
, I0 `4 j$ l. S# s# y6 k+ W    // time step.  The action is executed at time 0 relative to
( {3 u/ R, J# I& J: Z    // the beginning of the loop.
+ [3 B6 q* n8 q3 ~7 x: {
    // This is a simple schedule, with only one action that is
; H8 \, E$ a0 p3 g/ D* M    // just repeated every time. See jmousetrap for more
) [+ c* E: q# o1 E; ]8 h+ m$ f    // complicated schedules.
) m5 K; j! ]# ?# v  
7 E% V! S7 j) N+ }- R: W    modelSchedule = new ScheduleImpl (getZone (), 1);
+ t4 A! j! _- ^$ {" Z. ~    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }