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：
  g4 T7 {. u& c, I
public Object buildActions () {
3 G$ n% T1 s9 p6 f, V2 D3 u/ N. H    super.buildActions();
   
- s) P, J: F: g, @$ s+ W1 u    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
' M2 k- O, b9 J/ }) E    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
; o5 t' M- a7 h! Z& x" r  C& t; O    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
6 Z, I+ z6 }* }: S9 i$ x% T; T        
  R) y. `# k; v& J, X    // Note we update the heatspace in two phases: first run
# x( e4 a$ ?2 x. J( ?, _3 {    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
, b. a" Q/ K# }/ K1 w$ a    // significant!
* T$ e1 }& T+ K+ R- H& R' \        
3 l' x7 e% J/ l. I7 c* G; v    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
" u7 d* a, H4 C* ?' {3 _4 |    // randomize the order in which the bugs actually run
. i6 l1 A9 o" y  U% a* r$ ~    // their step rule.  This has the effect of removing any
4 ^: [) h0 n' |/ e" t: i    // systematic bias in the iteration throught the heatbug
# l5 z+ N5 a+ J2 E1 B    // list from timestep to timestep
' h9 ?$ Z) W! v% {8 d8 z, w- o        
+ C' ~" }# w2 z2 t5 x: K9 w. V    // By default, all `createActionForEach' modelActions have
" `. h- D" D" u1 b& m! \    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
4 P* h$ b. E5 [" i+ _    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
9 L+ q7 z8 W9 i3 ]% ~: z. Y, L( Q    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
- E6 a% Q5 o/ m) _    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
4 i( N6 j1 k) c) c. b' P      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
8 J5 _  m- n# J: J( ~! [" [   
    syncUpdateOrder ();

" l' P0 P5 h8 F/ s; F" {8 I    try {
      modelActions.createActionTo$message
) g% Z) \% c  N        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
8 c+ @# {- y& h( U) T      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // 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
    // 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
    // the beginning of the loop.

% \7 x' l4 j* h# c( {$ y  ?    // This is a simple schedule, with only one action that is
/ q, f3 j) S% x9 d' P    // just repeated every time. See jmousetrap for more
    // complicated schedules.
# F; f9 m2 s/ m; q4 U  
    modelSchedule = new ScheduleImpl (getZone (), 1);
* K1 `/ W# I2 ?, I1 r+ \8 }$ [    modelSchedule.at$createAction (0, modelActions);
        
- `1 a1 b; f+ n! @( H. K! F( _' q    return this;
  }