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：
( H: \  A" {: @- {5 b
. t9 ?- o/ n2 e: s  \- B public Object buildActions () {
    super.buildActions();
   
+ r" v! Q' f1 Y4 n    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
' Z2 V1 d5 E! Z& r( W; a% Q2 f    // executed in a specific order, but these steps should
    // 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.
        
; \# ?; v; M- k/ x, t5 Q. T: S    // Note we update the heatspace in two phases: first run
, }9 W& [2 z7 K/ z  J. o    // diffusion, then run "updateWorld" to actually enact the
, n5 b" ]; ^2 V& e* I/ Y    // changes the heatbugs have made. The ordering here is
    // significant!
5 g# T& S1 ~  T  ~8 `+ v        
    // Note also, that with the additional
) r1 h! ^0 V# l5 P) |+ ?; Q/ g# k    // `randomizeHeatbugUpdateOrder' Boolean flag we can
; v' x% C2 d1 y    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
5 {! c# \7 N+ ]; g* Y* W    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
! M8 S! a5 O" X    // 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
6 }, H# a$ O1 z2 j1 K- u% @    // indirectly by some other process).
   
& z/ R$ v0 ^/ G$ f  [, [7 B    modelActions = new ActionGroupImpl (getZone ());
: O' x' v& |' @  E
    try {
* o" f  f5 ?' p2 U8 p) r      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
* b6 ~% }! d" f! K6 K) f2 v& ^      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
9 N3 z+ ^; v& P) v: O0 L2 l3 ~
4 w# z4 p' }6 C2 H$ i    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
4 f9 }! e1 D# Z5 |% U      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
1 B7 ^8 h# I. b" i1 A2 a2 t9 U. i" J        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
* _+ K  X' t, E         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
; a( C$ Y  J  C: M( X  ?    }
" [2 J8 E+ y6 N) r   
) l* _9 k* O0 W8 |, L" T0 q- A    syncUpdateOrder ();

    try {
. j2 ]7 I& ^  U+ R$ e/ K1 H      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
9 ]5 X$ g9 }5 R: i    } catch (Exception e) {
; m: J5 k+ T" S/ W      System.err.println("Exception updateLattice: " + e.getMessage ());
  L. H) b& {6 y$ y0 C    }
" K9 [' U% D4 F8 x& T        
    // 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
/ G% Q7 T: M4 Z# c- T# g  Z  o7 m    // modelActions ActionGroup at particular times.  This
' A& X: `! B' y5 c2 \/ j' a1 D    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
; D# a4 n- H: I) e) ^: B% p+ P    // the beginning of the loop.
' F. {! i4 W. {4 }
$ l4 ^$ Y0 ~9 s5 N" ^    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
2 [2 s+ N1 F+ r0 C. z. s; E    // complicated schedules.
% x, t! f0 k/ q- C- a7 d7 X  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }