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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! d/ b$ [, [4 i4 M! m- { public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // 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
5 y2 j$ h3 K5 B! M    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
& a( T! ^7 u1 s) T& n* \( x; r1 t* L        
    // 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
4 ~! e$ q. _# y    // significant!
        
9 }/ a6 @" _0 \$ D$ L8 @; U( t. o    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
1 H- |* a( C- W9 K. G* C    // order of iteration through the `heatbugList' will be
. H9 |6 N+ n8 I1 G5 E    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());

  _$ b! m% p  n& t" O$ a    try {
0 {. U! ?2 z3 u+ \- O8 ?* W      modelActions.createActionTo$message
9 }  D' x2 w/ d        (heat, new Selector (heat.getClass (), "stepRule", false));
' }$ ]- U4 q4 e+ }5 J" s; l    } catch (Exception e) {
/ c. F$ u. t9 e1 g# R      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
1 k. Y" h; `8 w4 F% }7 o& U      actionForEach =
1 B. s. h; X) s/ S, A& r" }$ e        modelActions.createFActionForEachHomogeneous$call
" W5 M9 M8 e5 j, N+ {8 `, q        (heatbugList,
! @# b4 @: }5 `& W2 W* C) n" x0 l+ w: G         new FCallImpl (this, proto, sel,
. ?' ?( Y2 a: _& F7 N) z                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
+ f' p' M: o6 g" N   
    syncUpdateOrder ();
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1 w) T# R4 Z* M( f& m, a    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
( J' x- K- M- c# o+ N    }
        
    // Then we create a schedule that executes the
8 ^+ I! Z/ |- N" F0 K# B    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // 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
" K9 ^/ j: f7 k8 v    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

+ U# s3 M* T2 m    // This is a simple schedule, with only one action that is
* v1 W7 \5 X' x" h; ]    // just repeated every time. See jmousetrap for more
" H( T  ]# Z, X8 g    // complicated schedules.
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    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
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" X) B. l! m/ d% x3 d' g& r    return this;
3 n7 C7 ]' S2 P0 A% Q6 N, U  }