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：

& \% |8 d/ h/ O% F$ O5 j public Object buildActions () {
6 `" r, G+ |0 l% b$ X' X    super.buildActions();
. F- ]1 A9 T# U3 R   
' J: _7 l2 Q1 }& B. U& k    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
% l; v: L% o: Z' _: s$ ?# w2 I    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
6 v2 g& y/ u; h9 e$ U1 i    // called <foo>". You can send a message To a particular
- J: x& Z, I. ]# x8 k4 Z+ l0 a    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
) f, e, O9 H! P1 M9 [/ O4 a    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
  L7 e# K+ y6 o$ i    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
) I8 y$ w* u# \" Q& c    // systematic bias in the iteration throught the heatbug
0 R' c: e' \) y! u: z5 k    // list from timestep to timestep
. p0 w' w3 U! S" `" ?        
    // 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).
1 `. {' G8 Y* s! T( r) l/ @8 c   
0 p, A; D6 b8 {, [    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
7 X- S4 D0 u5 s6 X* `% R+ z& ~      System.err.println ("Exception stepRule: " + e.getMessage ());
) n2 P1 W: p* ]3 U: G1 E' ]    }
+ K1 U) d; }9 v: j! ~! T
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
4 F( f& [- h0 ~4 z: F( v      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
: \; B8 B1 i$ ]8 L. B; L      actionForEach =
6 c9 H0 l; @( g! Q+ b9 W) M* F        modelActions.createFActionForEachHomogeneous$call
; f2 y$ q8 S) ^  E1 P# }        (heatbugList,
" N# f0 e# g9 J; {+ f( p( E' U* w# Q         new FCallImpl (this, proto, sel,
$ |7 {4 L0 B6 M) J                        new FArgumentsImpl (this, sel)));
; T, f9 F5 R+ c& Y9 n3 t9 h3 t    } catch (Exception e) {
1 l# P2 }7 F) S6 B: O      e.printStackTrace (System.err);
; O( u" ^- D- t& G' N: i    }
: ]9 I, ]+ R! v' s   
7 y, G; a/ S* N- M/ [    syncUpdateOrder ();
$ b! `$ P+ L. ]# G: K
    try {
3 {: V% ]# K0 i9 y1 f      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
$ J* }. E) a$ U; X0 u8 k' k$ w5 y, C        
    // 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
; ?' p/ n" F; M- g; d: X: ]0 ]    // modelActions ActionGroup at particular times.  This
* v% }4 |/ F7 t) n/ s    // schedule has a repeat interval of 1, it will loop every
1 l3 ?) r5 W5 t! i, }* @- u, T    // 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
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
! d! P& Z. U3 s+ x0 E  
' \. a# V/ r0 W+ m! O2 b; F7 }    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }