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：

public Object buildActions () {
/ r& T$ u  U( \/ o) x    super.buildActions();
. H" w* F' E, r7 S   
+ K+ A7 f( E5 }1 |" l% K    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
* Q4 @  T' d# B    // 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.
5 I% G7 b9 A4 |( b6 P        
    // 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!
        
5 l% R1 ^6 P3 z8 a- _! Y' d+ f( A2 o4 F    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
* u: e. ^- ~/ |. z    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
( U1 c3 ?* [% i% ?) B' [8 s    // list from timestep to timestep
        
$ S8 e- r6 D/ n7 @2 Z% ^$ y/ T' a    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
! U, B! ^8 M, W5 S2 v' ~    // order of iteration through the `heatbugList' will be
8 O* M7 f4 m1 a7 m) }: R/ Q! K    // identical (assuming the list order is not changed
    // indirectly by some other process).
8 k# x: n- D, k: o  t$ S2 x   
    modelActions = new ActionGroupImpl (getZone ());
1 }" ]" s- @6 A5 ^" x' @" g3 A
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
+ x, I3 S. w: ?, q4 x1 A    } catch (Exception e) {
+ b7 K! J8 F4 i, G. q      System.err.println ("Exception stepRule: " + e.getMessage ());
* V6 Z1 L6 \* v4 s, T    }
, ]4 I3 P2 w2 f9 L. G" w" W
    try {
0 |# t4 F! Q% Q5 H: j      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
  G! ]7 D' R3 j7 o4 {! c9 f        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
7 D8 L" Y! u6 U( b! }  f         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
- d) e) H* D: A: Q' x# Z; A4 |5 j   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
( E( g- X! l$ d# a        (heat, new Selector (heat.getClass (), "updateLattice", false));
  i* U% Z2 i8 P- `/ W# `/ c    } catch (Exception e) {
      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
# A7 V2 Z7 r8 h1 v7 }; q' j    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
: b6 ]& f6 P; d9 X$ N, G% I    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

. _4 t/ V) K# u. W3 K    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
+ [$ J" O. Q8 z% W' G5 x    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
% }* ]$ l9 R' l4 i+ s    modelSchedule.at$createAction (0, modelActions);
. a! D4 d! X# ?, }) U) C( P        
+ K+ ~* }3 w7 m% L7 U4 O# [6 u    return this;
  }