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：
% L! n) K' o/ x
( F% u0 _) i4 U9 u1 `& g+ O public Object buildActions () {
    super.buildActions();
   
2 v8 r/ [) T3 h& Q    // Create the list of simulation actions. We put these in
; v# L1 k7 U) Q- }" @    // 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
    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
9 K: i0 p8 ~) L! b% c7 p    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
8 t- S! F7 f7 C; p# i9 j6 H        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
; b9 B8 n6 ]5 R( j9 }( E9 e    // their step rule.  This has the effect of removing any
: a% d- m% T+ l4 t2 G3 u0 F. f- a! ?    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
6 P# i1 A% T; z5 R; W3 t- ]        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
! D# w! }5 g' R% |  H% s! g' a    // order of iteration through the `heatbugList' will be
7 @' \( S6 I) _8 a    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
3 t/ Q/ {; K$ \: @( j    modelActions = new ActionGroupImpl (getZone ());
+ D3 h+ ]+ v  y7 T9 S- D
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
7 q( k' X3 d; `! t+ e    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

5 I! @3 X/ d- r7 F8 {- Z9 W    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
( P5 ]+ a: c* y4 n" F# H9 l      Selector sel =
9 k9 U0 m4 _1 s5 g8 A+ N0 K        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
, Y1 {# P. t* T) ?  |( n) K         new FCallImpl (this, proto, sel,
. r' _6 ?0 U7 S3 o                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
2 O5 s3 D! S2 k) `+ v0 h5 b* c, ?    syncUpdateOrder ();

( B7 u6 f% {2 s5 D+ ^6 G    try {
7 z5 W4 O- q& e1 o      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
; G7 i6 V) m; G7 v7 R+ x7 o    } catch (Exception e) {
6 n% Y3 X5 Q  U/ ?/ n; r      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // 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
) J0 a' _0 ]) E4 |5 Z# _    // 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.

3 y2 F: l5 E: u    // This is a simple schedule, with only one action that is
' L" C* {4 Q& B- d; }6 O    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
5 u8 j* W" y, Q4 }% `* V: W1 r, E    modelSchedule.at$createAction (0, modelActions);
        
) }2 L8 [) ?! w4 V, ]    return this;
  }