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：
& v8 i0 {* q% [3 ]+ `
public Object buildActions () {
    super.buildActions();
   
    // 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
) }; e8 v6 K, A) Q! |6 W% l( [    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
% O6 _, ~+ U, T: H/ m* v" _: Z        
    // Note we update the heatspace in two phases: first run
+ t" _5 Q/ C/ K. {+ Q8 ?% X* }    // diffusion, then run "updateWorld" to actually enact the
' p0 a' i2 l$ L! D    // changes the heatbugs have made. The ordering here is
6 l* P& D& R* v/ C6 ~    // significant!
$ F6 l; T' h! j        
    // Note also, that with the additional
" {( q$ k) c# U; ?5 a  v5 |4 G    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
+ `) z1 G0 R) B# T    // list from timestep to timestep
        
9 f3 m4 m6 ~' w; J, s* b    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
& q7 P& v) O3 V2 N    // order of iteration through the `heatbugList' will be
* m3 M2 w8 H" u- L    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
* t: |; s  G& G( h    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
( S, {  A; y7 V3 I        (heat, new Selector (heat.getClass (), "stepRule", false));
8 m9 j# e/ j3 `+ Z8 E    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
" l4 H0 l# g1 d5 k    }
9 H2 T: F$ i0 h9 C
, k# @. f6 J* v/ E    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
8 J- @  N' q& s, Q- }: [      Selector sel =
% a# u0 a2 ^; Q1 y8 U        new Selector (proto.getClass (), "heatbugStep", false);
6 U0 m4 o2 F9 j( P- V: w* I3 V      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
& W. d3 x8 G$ j* \5 n2 y0 y7 G    } catch (Exception e) {
- Q8 ?  B9 ]9 v+ I4 M      e.printStackTrace (System.err);
) ]2 J$ J) F" _- G9 K/ v    }
   
- I+ i* ^/ }! X( ^; p    syncUpdateOrder ();

; r9 k* l( p+ x( M& k$ j! I" P    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
# U4 k; f+ ^8 ?      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
& B0 t  e! \+ l% t5 \0 r3 y- b        
! u1 N/ e! w' w# W    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
; q+ }2 X& t% u- O' S    // 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
) `- E1 X% H' Q& i' S& c( C* @    // schedule has a repeat interval of 1, it will loop every
    // 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
& A9 b0 T& g! f+ E) Z7 V    // just repeated every time. See jmousetrap for more
    // complicated schedules.
1 a% C8 v+ {- e! h  
1 U. W+ B' i! n. ]' F5 L    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
) o' u# u: H; J1 s+ u/ P2 `6 m' [3 E    return this;
  }