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：
9 B9 Y" z- m$ l2 g5 t
- a6 ~1 c6 g. H$ s. {" I public Object buildActions () {
" K% }8 ]. Q6 |4 D" S2 Q    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
" o+ r% l$ `8 z) `- v- g, W    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
) u1 S% a2 z6 ?& i& D    // called <foo>". You can send a message To a particular
1 m: w5 y4 T1 d0 p- ?! B, I    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
; a- M& P- ^5 x) ^% @) T    // significant!
: k  N* j& }! J  b/ g        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
( I6 d1 b' L5 @- f: F4 u6 p* b    // 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
. \+ s8 T' U" X    // list from timestep to timestep
6 w; N, w  @! q6 H7 V        
/ K+ s! F" c  m9 d( _    // By default, all `createActionForEach' modelActions have
2 p$ b# j! e" R. S3 e( ?: d8 Y    // a default order of `Sequential', which means that the
  }6 [% u& W$ B    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
) L+ q  k$ f. {    modelActions = new ActionGroupImpl (getZone ());

    try {
6 M' I, f  V$ S5 H      modelActions.createActionTo$message
5 ]8 X$ @6 N  h, H# c2 P        (heat, new Selector (heat.getClass (), "stepRule", false));
6 o0 y& c! a" w0 r' z    } catch (Exception e) {
$ X. z1 ^+ |' X- X8 J5 ^; f      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
4 Z2 \# Q6 w. S: }        new Selector (proto.getClass (), "heatbugStep", false);
  [/ a/ Q, a0 M! b* r) U      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
' [# F. T! G7 p, t. K. A                        new FArgumentsImpl (this, sel)));
  g5 g0 x$ \* s3 \! l" ]    } catch (Exception e) {
      e.printStackTrace (System.err);
: _' E8 d' G+ n8 X  N8 V# `0 ^    }
   
    syncUpdateOrder ();

8 ~% O; U! e/ A5 a& u    try {
; n' i! V# s9 f$ t1 |5 C      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
: t+ m1 M  ^/ o' f1 o    }
        
% n' J" `4 a7 @# E* S    // Then we create a schedule that executes the
8 D( I2 B- y* Z5 Y* i( s" F9 n: I    // modelActions. modelActions is an ActionGroup, by itself it
( P% i7 |3 h3 `9 {& q3 H* F  c    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
. a" ?* W8 P5 z* m8 c) j0 n    // modelActions ActionGroup at particular times.  This
9 y, @) d4 G, S1 a    // 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.
4 t- p4 q) i5 k6 r$ q
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
  J7 q  u  @6 N2 T- a    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
% r- R. |4 ^. S* e# n        
/ v% J3 \) p& R" r    return this;
  }