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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public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
: q! t( k' v- U& x" o; ?- `    // an action group, because we want these actions to be
: ^. |0 r- Y1 x" `# L1 P1 t  }) m% n0 f    // 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.
        
$ a9 r8 a5 L+ R$ ^    // Note we update the heatspace in two phases: first run
8 d6 e3 i/ q7 F0 g: U    // diffusion, then run "updateWorld" to actually enact the
; v/ d" Z, e7 E( E5 h: G    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
0 d- k7 C3 q" Y  i  \    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
# O; N! P' t2 V8 ^    // their step rule.  This has the effect of removing any
* b1 `" K8 O  t  A3 m& Z    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
, T. d) j) L4 ~; t        
  g  k1 K, ?+ z! K9 Q. Y0 j4 U    // By default, all `createActionForEach' modelActions have
( Y6 u9 p/ W. L% }& g9 a- d8 f3 ?    // 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).
# P. ?% ]8 s' N( z& H# w2 Z. x   
. }- g' W" T- B$ t    modelActions = new ActionGroupImpl (getZone ());

; J$ f" K: _  T+ T1 n    try {
      modelActions.createActionTo$message
) N7 o- |0 r7 v* z        (heat, new Selector (heat.getClass (), "stepRule", false));
1 N) U2 s" {) A1 ?    } catch (Exception e) {
: k+ U0 G0 @7 q( f4 X" \6 p      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
9 y* u1 c( L5 C9 P% F. T0 f. \
    try {
/ W! s# u+ Q: w      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
, N. G! A! j; z5 u- b# f$ I      actionForEach =
( W9 {* V( v! _/ I% p/ L+ r$ [4 a/ l3 G        modelActions.createFActionForEachHomogeneous$call
0 ~: p0 r) \: ^4 R6 M) s, h        (heatbugList,
         new FCallImpl (this, proto, sel,
7 n4 R9 _! J# Q' Q+ y                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
# _: x( Q4 n9 _; S1 D+ S    syncUpdateOrder ();
) j  e8 f! E/ D- m4 Z
    try {
& t/ b. T) H: r      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
) _5 |' V+ z" E; K4 p    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
3 R* h) u8 Q& W! x9 D- j% E- x    // modelActions. modelActions is an ActionGroup, by itself it
+ h+ B8 Z! n2 |5 p* ]" V    // has no notion of time. In order to have it executed in
. d0 ]0 d" L9 T    // time, we create a Schedule that says to use the
4 P: `4 s( [: l1 {& |    // 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.
5 K7 }& q9 ]- d5 H0 }% }
    // This is a simple schedule, with only one action that is
" m$ m/ L- _6 N! V. \( U3 t* _    // just repeated every time. See jmousetrap for more
! X) \9 a2 x- v7 m1 d$ o    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
; L- y5 B; _8 U6 B    modelSchedule.at$createAction (0, modelActions);
        
  _5 D2 F8 W& Y) N! K    return this;
  }