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：
# @! L5 Z1 @% B4 ^
) ]4 I7 t% _& G7 }' d+ Z9 R public Object buildActions () {
    super.buildActions();
5 \: x% `  Z, w9 g   
; U+ E3 h, H: `* w% K2 R* v5 y* M    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
5 f0 K2 g8 A  _+ S4 _! K) q( d    // 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
$ Z4 a8 W  F/ ?, d- W: F( e# V    // object, or ForEach object in a collection.
        
# s. s! l, g9 J0 @1 S% s) O5 S    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
7 g9 C, a4 F8 Z& i) N7 l    // changes the heatbugs have made. The ordering here is
    // significant!
        
! W* a& f; s* e+ o! K& @    // Note also, that with the additional
# ^/ p$ }- I( r    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
& B: `" u! B0 A0 r: J    // systematic bias in the iteration throught the heatbug
( n/ V) z% X9 ~: m" e    // list from timestep to timestep
+ _0 _6 ]) G/ q0 i        
6 w6 F. r2 y. V& |0 D7 k' X3 j    // By default, all `createActionForEach' modelActions have
; ]" A3 }) l" {0 J. z    // 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
- N- [* J  a# b0 T0 o3 u! G    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

    try {
/ `- q' }# p4 V9 K" N      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
1 E9 p: b, X) \: [, o, b      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
6 a* d, \5 I3 V$ Y/ U4 p$ x2 \
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
) W1 Q7 m$ m% Q  }5 a      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
7 A: C& Z8 D4 S$ {    } catch (Exception e) {
8 Y0 O- U4 ~/ s      e.printStackTrace (System.err);
5 D2 |1 n* P0 G6 M' Y    }
   
    syncUpdateOrder ();
/ ~0 o5 A$ M8 V6 f" }& Q5 C, L
5 V! i/ x' i. Y* q& P1 A: Z    try {
0 b9 b- |8 o) U' Y/ R: ?      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
) S( _( O* j. G# ]/ \    } catch (Exception e) {
0 V" `7 X1 ]: u& X+ q) `* `* }      System.err.println("Exception updateLattice: " + e.getMessage ());
' S" j8 O; }4 F% X9 V    }
7 j: O* q* J. x8 J( Q( Y6 I        
. s+ }% x/ W$ `, ~8 A    // Then we create a schedule that executes the
  T5 |' T8 ?4 B5 d* `    // modelActions. modelActions is an ActionGroup, by itself it
& `, ]5 F8 g5 Q6 A; m    // has no notion of time. In order to have it executed in
6 j2 q5 t, e/ y' |5 N1 p    // 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
; a; {& j9 K; y; d% y3 A    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
) q/ ^4 e3 G. d; b4 P
    // This is a simple schedule, with only one action that is
" V8 ^7 D6 y5 {3 n4 D. S4 `; W    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
9 O2 l+ W* e  E, s" c    modelSchedule = new ScheduleImpl (getZone (), 1);
' K7 A$ g) u) G) X1 k/ C/ v2 }    modelSchedule.at$createAction (0, modelActions);
        
/ v8 n5 Q9 p; U6 r# O* E    return this;
  }