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：
8 l& k2 t- H4 {! j9 K1 `0 v' T
public Object buildActions () {
    super.buildActions();
: ~; M) r& I% o, ~2 _# {: [   
1 w  c4 m; @' e5 J4 m    // Create the list of simulation actions. We put these in
2 o3 x2 o, h7 ^* z1 X" S) B    // 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
, T9 `2 j3 L* d$ X) g    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
5 @4 |& P9 [3 P+ s" U        
/ n  D# {& W: s    // 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
    // significant!
4 @, C- }( C5 H, Q        
    // Note also, that with the additional
1 [/ n; x* I% a( o' U    // `randomizeHeatbugUpdateOrder' Boolean flag we can
2 G. l) v( v( z# v5 g; z& }    // randomize the order in which the bugs actually run
# `  Z- i+ i4 @* z$ y! d; i2 w    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
2 y# U1 z0 Q! \    // list from timestep to timestep
: t1 }* x3 t" }        
    // 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).
! [" r1 e- T& z4 ?   
    modelActions = new ActionGroupImpl (getZone ());

    try {
+ V  Q6 i* C9 G- V      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
7 G  T' G  ^. L' x7 z, n4 p2 m) f    } catch (Exception e) {
) Z$ J# O' I$ z% [      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

! c$ g6 k9 L; n+ N& o% E: Z    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
3 K6 Q8 ~# i8 f2 J* h. q: @    } catch (Exception e) {
* V  n9 }' n- T. I! q0 U' D8 p( I* y: I      e.printStackTrace (System.err);
6 B  a& H9 C5 f5 r; ]- z    }
   
    syncUpdateOrder ();

; S8 u& R! G1 P' B5 t9 H- O" o8 R6 Y    try {
( h5 a6 f; V3 W  n, J      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
  J1 f) q; A+ u1 R      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
) o- _& S5 E* I0 t( O! {    // modelActions. modelActions is an ActionGroup, by itself it
8 A: R5 ~$ S$ {. ]% I1 V    // has no notion of time. In order to have it executed in
7 ?$ d2 k  v4 @6 }: J  {: \    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
5 H3 b- [5 n1 k4 D$ _8 ]+ d    // schedule has a repeat interval of 1, it will loop every
7 g2 X; O) p7 j( ?0 D+ K1 W/ o    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
$ `6 H- z( R( y    modelSchedule = new ScheduleImpl (getZone (), 1);
, a: e$ n3 Y7 h( {( v    modelSchedule.at$createAction (0, modelActions);
3 c! p: c' F5 c7 z& C4 v' @        
    return this;
  }