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：
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6 f7 `; r6 L0 r/ m# _/ s8 _2 o public Object buildActions () {
    super.buildActions();
  S* a+ @9 o8 W- ?" _6 E   
1 V$ V3 g7 Q  X7 F6 j  V! K" n    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
2 N) R& s% m: j. C& W4 d0 a0 U. O    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
8 d1 l5 p- _' z8 ^* W    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
% D  k; G9 _5 L' D$ u        
    // Note we update the heatspace in two phases: first run
; M3 i7 ~! `0 |0 V  m    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
* R7 F% |3 }' o$ b        
) G7 d0 M- W6 i( T9 G4 a  @    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
) a: g6 {( G5 F( }% K' J  [    // 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
, v2 O+ o$ c! f" v% P    // list from timestep to timestep
, }  y, W8 n6 O        
    // 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).
   
9 t3 Y5 M. l: L* h/ n    modelActions = new ActionGroupImpl (getZone ());
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    try {
/ h; T* f8 J- V      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
; P: i0 t% A% A- d" c    } catch (Exception e) {
( T: {& Q4 [: ]6 M: T5 j) \+ u" {7 F      System.err.println ("Exception stepRule: " + e.getMessage ());
' }# G3 X2 y6 m) e9 n7 Q    }
) d# o7 ?  s# B6 h, h3 I
    try {
' m! S- c+ i9 X" W" s      Heatbug proto = (Heatbug) heatbugList.get (0);
/ N! Y1 n' O5 k: B6 `0 s      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
: h2 x) ^! e3 r  t# S. _4 Y5 x        (heatbugList,
. i* H0 t! H6 G1 f9 _0 Z* ~2 o         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
! M  w6 N8 a5 }" u* B0 D5 u+ p( }      e.printStackTrace (System.err);
    }
   
+ t- g4 B! p( L) P8 g0 `! E    syncUpdateOrder ();

    try {
" E; L( ]' J! ~8 \( P  z$ K      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
* e9 l' |3 u+ z  X# \1 K  u    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
' E) Y) c5 ~$ t        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
( {+ d  u4 F  r" q* I) m    // has no notion of time. In order to have it executed in
; H4 u8 J9 k& }' V6 B/ t    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
/ ?9 ?, |! ~" k! D( v4 A( w. Z& g    // 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.
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    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
6 v6 N! k8 [# s% q# b1 Q: U  x2 M  
6 R. u! j. C2 S4 C$ J    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
$ u; ~. z" ~/ A2 E: v0 E; c3 p  }