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：
$ W+ B/ _5 _  g, \9 P
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
    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
# t2 j' w6 {- x2 @2 e        
    // 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
    // significant!
4 t: @7 a; J6 X8 V% c( ^7 d- c        
+ h2 f8 j' K- x+ v! z: e    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
) S4 Y6 }8 a) v& f2 T% ]$ I6 o    // randomize the order in which the bugs actually run
& b- e. l, }; Q: }' u    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
- u- ]" Z5 A/ d0 p$ b& K. ^. G    // list from timestep to timestep
        
; h, t# @7 E# C3 B    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
+ f- c* k9 }. _    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
  a2 E! V$ S% ]  q: B% |   
    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
, O  N7 z0 n+ B, ^    }
/ ?0 S6 d0 G' e' }1 [
/ A! B  Q$ j+ F0 V8 w% N6 b- ?    try {
) F2 y" I% n( D' W: a% z      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
- e) R% v9 W( f; ?        (heatbugList,
" v) P6 q' K  {. `. L0 P/ e2 h0 \         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
  {# A  e0 H  n; ?; b    } catch (Exception e) {
      e.printStackTrace (System.err);
3 e5 U5 k6 {0 L2 M    }
' H" B; l- x8 A& H3 B   
& F( z8 u: i* ^! o5 p, b. y    syncUpdateOrder ();
8 z3 C+ W* u3 M! a6 ^2 _8 i
    try {
+ V, W  p8 R# T      modelActions.createActionTo$message
, Q; |% j3 r# ~" S  M" k) r        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
# k( t0 |4 g# |$ l( k4 i6 L/ |    }
5 l  N$ [! N" X8 s# E! A5 z        
    // Then we create a schedule that executes the
. L( M8 W+ T9 X% E! f    // modelActions. modelActions is an ActionGroup, by itself it
  l' o$ Y! F' h2 {6 q    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
/ C' Z& h! O) h# e0 }/ Z    // modelActions ActionGroup at particular times.  This
) s8 S0 A# B7 S7 E2 V+ h! }0 l  o5 ]: X    // schedule has a repeat interval of 1, it will loop every
. R  _2 C, h# U) o9 v& q    // time step.  The action is executed at time 0 relative to
+ V; ~- v- J" f/ C% t" D+ G4 t    // the beginning of the loop.
  J! S' o2 V8 ^  c' [8 }
    // This is a simple schedule, with only one action that is
5 {5 ]( f$ B0 J$ G# s9 o* [    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
. M! h7 P2 R- a" d    modelSchedule.at$createAction (0, modelActions);
        
( \/ s8 V% G6 u& J  f+ V    return this;
  }