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：
3 }; D4 i8 |5 H+ ]  M, K7 K
public Object buildActions () {
    super.buildActions();
! N0 A7 ]( a8 K7 M   
! ?! P8 y+ @3 a9 k5 O: o    // 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
6 L/ N& e" Z) B1 E: c# \    // take no (simulated) time. The M(foo) means "The message
' H# p, J6 M8 E3 j. \    // called <foo>". You can send a message To a particular
! R8 E# N- u! n; e. o0 h0 W" K0 ^    // object, or ForEach object in a collection.
  b: @% T- O, S/ O! z, S        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
" C$ K5 ~6 s& d9 G$ q    // changes the heatbugs have made. The ordering here is
    // significant!
5 S5 G6 L$ v0 l) n        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
' r* t" n/ l" y. i    // their step rule.  This has the effect of removing any
' O/ M. m1 ^" a3 v0 F    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
  g+ o( u. U, d7 o3 G  ?    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
8 g; W5 q* r' B4 N* c% b, i  s    // order of iteration through the `heatbugList' will be
4 Y1 b  ~. m" q9 W" z    // identical (assuming the list order is not changed
    // indirectly by some other process).
3 B/ L& Q/ s' c5 N. S7 W   
    modelActions = new ActionGroupImpl (getZone ());

9 B+ H. N0 g6 _) s) b- |    try {
      modelActions.createActionTo$message
8 f( }: U: t! f: c8 {. y- t        (heat, new Selector (heat.getClass (), "stepRule", false));
: I7 D! r) w5 R9 l8 O    } catch (Exception e) {
2 p5 ~3 g  o  X, [8 ~8 k% K0 f& X      System.err.println ("Exception stepRule: " + e.getMessage ());
5 _# K* V) o$ L. P$ a    }
* `$ P8 }& J8 w" H
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
0 }2 e7 i& J- H8 n5 M6 f% w$ u- D, \      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
$ i0 |3 e4 @8 n% B- B' L) u. k" f      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
' F: G" n8 K1 H) E    } catch (Exception e) {
: d+ ?& A* j$ E0 c- X      e.printStackTrace (System.err);
    }
) u; o5 T6 X5 F6 p0 ]   
    syncUpdateOrder ();
# s" a' t7 U* g5 R  X; R
0 ^- C& Z$ M) S6 B    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
/ o8 f1 }3 l0 r/ W! E9 @- G: d    }
        
" u( j2 Q0 l! d" u# b: b    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
# H& \% u0 p% {8 p7 _! S9 W    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
, p$ D. V: @/ p! C$ v    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
+ T% n8 Q+ l. a  X    // 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
4 e$ P* J7 L' l. k* h* H7 J    // complicated schedules.
% E2 {, U7 U+ I2 c  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }