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：

public Object buildActions () {
9 z8 n! C; l) e# U, F$ o& J1 U7 M9 g  S    super.buildActions();
   
: Q- b7 D! [* s( T( I    // Create the list of simulation actions. We put these in
+ \. ~  T, G/ C) H- d    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
. N$ G1 Y$ d, Z; c) P+ F    // 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.
. F$ G1 O1 C3 W1 _& }        
    // 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
0 ~. w% f* P7 @    // significant!
& u5 G7 o: ?( F% d        
    // Note also, that with the additional
4 ~0 ^# j4 d, K+ e9 G' c- D    // `randomizeHeatbugUpdateOrder' Boolean flag we can
$ z4 @5 ?. `8 T    // randomize the order in which the bugs actually run
, Q5 h# M" {2 w" C    // their step rule.  This has the effect of removing any
5 Q1 h+ g$ Q  |3 U. D0 D    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
- k3 d( R- g% p4 k) m+ c- j4 Z. m        
: x5 u' c1 `8 D  I7 t* V    // 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).
: _- O! Y0 J1 |" n4 G5 K1 N   
    modelActions = new ActionGroupImpl (getZone ());

    try {
% C+ N9 T- M8 K! T      modelActions.createActionTo$message
$ U+ k$ X) ~2 }5 N        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
# R  j4 y( @# t' @3 m      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
" r& _, y" s  O, q; v9 e% V      Heatbug proto = (Heatbug) heatbugList.get (0);
0 W8 R' f& z& b0 @, V$ Y) {      Selector sel =
' L- f) L5 Y6 m5 w. C6 d( W        new Selector (proto.getClass (), "heatbugStep", false);
6 ]3 n* X0 u) m8 c* F8 T5 k2 N      actionForEach =
& d5 D& x5 w/ E0 S        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
7 W' I; |/ [3 W6 r; m3 g    } catch (Exception e) {
/ L% t& A, [: d  V' x      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
$ M! e; o1 i3 O! R: g9 T& [6 y
    try {
4 |. G1 C. q0 u5 F      modelActions.createActionTo$message
5 j8 ^  y# O' p! m; K0 f" f        (heat, new Selector (heat.getClass (), "updateLattice", false));
, Z0 v# o5 g) x& ^, |3 v4 M& p    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
0 ^0 T, g0 E' g. k+ S    // Then we create a schedule that executes the
# E' o* E" R: u* i+ J2 m) C. y    // 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
    // time step.  The action is executed at time 0 relative to
; s) @$ ~" [7 Q1 ~8 Y* k' H! L    // the beginning of the loop.
; w; {# \5 y7 i5 w
    // This is a simple schedule, with only one action that is
7 f7 H/ U& e( \6 v  X/ Z8 v$ Q" z    // just repeated every time. See jmousetrap for more
    // complicated schedules.
- T' ]# b8 e+ X. L: b# n# v  
9 F0 J  s, N0 l" L) f. r    modelSchedule = new ScheduleImpl (getZone (), 1);
+ O8 u' L6 }1 N2 N4 i9 v! Q* I    modelSchedule.at$createAction (0, modelActions);
        
# R- a, x" G% |9 r1 Y# h: Y: `    return this;
  }