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：
: I9 e4 X* e5 t" L( @  Y
9 H5 Y: z: ~5 m! H* Y5 v/ d0 e public Object buildActions () {
    super.buildActions();
   
, V) J6 Z; V! k$ P0 ]& g# Y    // Create the list of simulation actions. We put these in
1 L' d& Y& i8 t. r# F5 }. t' m- k    // 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
1 |4 n; `$ a0 i( m& T: ^- s    // object, or ForEach object in a collection.
( x3 ~: z- K3 T* m2 u        
    // Note we update the heatspace in two phases: first run
6 H$ c  X4 t+ ?5 l! W5 w    // diffusion, then run "updateWorld" to actually enact the
, n$ k  |% U' C5 Y    // changes the heatbugs have made. The ordering here is
0 b# K8 X6 ~; \5 x7 l7 p- w    // significant!
        
: K; a* x. j8 v1 l' c4 h8 |+ Z    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
, U* z1 P: U8 E- W1 C; I    // 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
    // list from timestep to timestep
% N' W9 L5 G8 l        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
3 T8 N" u$ b. L5 P    // identical (assuming the list order is not changed
4 `$ Z" Z7 }3 S2 G, n& J9 B    // indirectly by some other process).
   
: k' E5 G4 r7 f" u    modelActions = new ActionGroupImpl (getZone ());

: {+ L/ _- j4 }" e    try {
' T3 n' m. t/ o0 o- r      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
. }! U& c0 S) ]  Q+ H* _- F    }
7 J. C4 p- }. N, y5 H
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
9 l8 P0 [: W$ G0 ^6 k# G+ k" N      Selector sel =
& t7 h7 |; I: g3 K" `3 D3 D        new Selector (proto.getClass (), "heatbugStep", false);
3 r: v( Q1 |2 p( r' e      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();
" i+ X/ @, a; Q! g3 K- d1 p
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
7 s0 U9 d# R5 R7 L" D      System.err.println("Exception updateLattice: " + e.getMessage ());
" |4 B* C$ J/ P) p6 a    }
        
    // Then we create a schedule that executes the
) i5 q1 Q# b9 m! n    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
' d. N- Q- n' ~2 F7 n. O1 _4 P    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
5 t) x% i. A$ U8 H! ]8 ]% X9 U! d    // 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.
, t4 |; [: _7 ^& N
: q) n. T1 v# r. P6 q, X. V. V! m    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
( r' A; S* @& O  I: f2 v  
. Z, z  ^2 Q, i  ]; R    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
, w; s0 F, _+ M7 q/ D) k- Q6 u    return this;
  }