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：
. R4 a! A3 z1 l- P( A& c) X
( @0 S* d' X+ f; a! { public Object buildActions () {
    super.buildActions();
$ y. A  w5 f3 S0 A9 E1 S& l* k   
8 q: Y9 o# D2 H) q' X5 v2 A    // 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
" i. _7 D! }# J* e) E- o: j: b    // take no (simulated) time. The M(foo) means "The message
$ Z0 T2 z: a4 p* B) u, s    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
+ m3 ~1 J0 p* A( R        
; z9 s9 e# s. r6 Y3 ?1 G# d/ m& J    // 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
' d" [; W% E8 I- {9 k0 E$ x    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
# D  f% D/ K6 ~) \5 \( K# }0 I+ f/ ^    // their step rule.  This has the effect of removing any
  g6 K) q" A, Y) v    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // 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).
   
    modelActions = new ActionGroupImpl (getZone ());

+ t! s5 I( N3 d  _1 d9 E  A    try {
( {: z* e' Y0 Q3 i      modelActions.createActionTo$message
8 d7 t+ I7 R6 p        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
0 C- S# n8 k1 ?2 Q4 d) f5 L) \0 k/ ~3 S    }
7 N/ J1 G. p0 ^6 l: @
    try {
* K2 P  X7 I) K& M" M      Heatbug proto = (Heatbug) heatbugList.get (0);
; H4 V* c7 s/ p& R: [; `1 ]      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
3 ?/ N) n% l6 y6 S7 @  L      actionForEach =
" m) I# i9 c6 i4 J$ W        modelActions.createFActionForEachHomogeneous$call
0 K3 {  {. w$ \; S5 r! W6 G        (heatbugList,
1 i( s0 \; O  Z* t. B( E3 ^+ s! [. r         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
. Y, w! v. i, s+ I, e- c, e' p    } catch (Exception e) {
  h6 l; s7 g% s  N! `% U      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
7 e, E' Z: P; A: C8 {- F
    try {
# X( I5 E) g  a' [      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
$ B6 z& u6 x- l/ W- h9 Q4 G    // modelActions. modelActions is an ActionGroup, by itself it
1 `/ E/ g6 ~5 |) A6 o5 `* W1 @% U    // 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
6 {% y) r( z- M    // the beginning of the loop.
% }" O$ Z1 C5 C. ~& ]
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
( z2 Z9 L4 A) i/ D1 ~    // complicated schedules.
  
# F8 n9 ^/ C" l8 F& M( w    modelSchedule = new ScheduleImpl (getZone (), 1);
+ u& v# H4 H* ?6 _    modelSchedule.at$createAction (0, modelActions);
/ i  t* l: G1 R( M9 F2 S        
# X( I3 A6 `- A$ p6 N    return this;
/ ^5 X9 T4 D- y& w% d; F) t  }