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：
, j% c9 P) I4 X$ ~
6 n1 X, {, }+ ]( R public Object buildActions () {
    super.buildActions();
, ~+ i' m5 l5 N. U* e# [   
    // Create the list of simulation actions. We put these in
0 r: A- N$ W1 o3 s; @    // an action group, because we want these actions to be
8 S  J' s! _2 w+ c: a    // executed in a specific order, but these steps should
1 B. y. _+ O; y  v) T# Z5 |    // 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 @# f* v% k9 D    // Note we update the heatspace in two phases: first run
* ], A& D' h% O# d# ?& J# f    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
$ a$ U5 T- q, h2 b! L$ T    // significant!
+ m9 _# N9 D* v$ e* K1 p        
    // Note also, that with the additional
( \) {) K3 k, ^0 M& X    // `randomizeHeatbugUpdateOrder' Boolean flag we can
3 ~4 B3 \  Q2 q6 I9 z  f3 Y2 k( D    // 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
* G2 z+ B( z0 J( s5 G6 [    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // 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).
   
    modelActions = new ActionGroupImpl (getZone ());

    try {
, ~. j; t' T. I/ H  ~% |! b      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
5 s+ |& k4 S3 B6 A" m0 i% ^2 D- r      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
6 ]# @/ I# ]  _; }* u  U, h; Y) f: y
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
0 T) S8 g& D9 N! z) O, J      Selector sel =
6 f0 u- }3 S$ ]" G9 J. ]        new Selector (proto.getClass (), "heatbugStep", false);
7 r1 p  h7 k7 ~      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
$ x- ^& d) u0 {, C( b        (heatbugList,
' N* q3 D' h2 u/ W         new FCallImpl (this, proto, sel,
- |) t( x5 q! A! U1 i. l/ U                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
) ?. \* Y7 H5 N  t: h9 t    syncUpdateOrder ();
) N% G3 ?3 \* }
  [% W. L" b1 Y9 z2 I    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
: m( d  p5 D' X  h; n% S& [( M        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
1 s5 \! E2 S- O4 j3 J9 p* y    // schedule has a repeat interval of 1, it will loop every
  M; {  z, o* S    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.
6 B4 F5 y! C( e$ T
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
, L, t: T4 S( s" I5 ~- z5 l& q    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
: f6 J# Y# y- l  a    return this;
# l8 i( n/ _: @/ Q6 a' o% y  }