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：
# I6 v4 Q6 e5 n& m0 y: i
public Object buildActions () {
    super.buildActions();
5 m& m* p' N) j# `: h  s8 X# q! v   
    // 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
    // take no (simulated) time. The M(foo) means "The message
, G$ E0 L8 Z6 P  |; b2 z+ j3 T    // called <foo>". You can send a message To a particular
+ m. K" {6 @4 {; V$ t% m    // object, or ForEach object in a collection.
        
    // Note we update the heatspace in two phases: first run
" \2 s9 L9 J2 Z2 m0 B8 t    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
5 k- Y* q1 o: \        
1 V, M% l* j) M& k1 ]4 L# _3 F7 N    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
, Z' `1 k. Y( ?; P/ [    // 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
2 J- H& l3 g1 }8 B  o3 Y8 K' B    // list from timestep to timestep
        
) I. C8 o  _* F    // By default, all `createActionForEach' modelActions have
! r* ~+ ^/ f( J& u$ ]    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
* \3 Y+ B3 C& r8 I* f5 s+ B; F    // identical (assuming the list order is not changed
( O& N' T- C: a& b) ]7 c) k6 `' F    // indirectly by some other process).
7 a& s2 T( C/ J   
    modelActions = new ActionGroupImpl (getZone ());

' F; L1 I0 C7 {( V6 A    try {
      modelActions.createActionTo$message
0 F* K* r5 T+ }4 s6 U        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
4 J- J$ f+ |1 p- v! j. d7 d2 |    }
; f. c9 {2 \7 x8 s
3 R7 N- Q) h. j& U$ x2 ~6 I    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
& [' k) x# {9 @1 L) F        new Selector (proto.getClass (), "heatbugStep", false);
- p2 U2 D8 a/ z0 ?      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
: X9 w' u- j  @7 ?    } catch (Exception e) {
0 n. Z# L7 J. x2 [' ^0 j      e.printStackTrace (System.err);
! H) V% H4 k  z5 K    }
6 l2 X- _1 h* y: T& E9 M* y$ S   
    syncUpdateOrder ();

3 b. w- @6 B0 E: B5 H( I    try {
$ }" z3 C8 K6 `# @: F      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
- t) b, J5 K, U        
    // Then we create a schedule that executes the
. C7 P; n& m. \) u- a" E- G    // modelActions. modelActions is an ActionGroup, by itself it
+ [# H6 u; B8 s" m    // 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
    // schedule has a repeat interval of 1, it will loop every
! c6 s. C. X% c    // time step.  The action is executed at time 0 relative to
$ y) {( u1 H' l5 z" x    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
( ?( q1 t1 F" o0 P* M    // complicated schedules.
8 m, c" i  l" T2 i  
    modelSchedule = new ScheduleImpl (getZone (), 1);
5 n  d4 [0 _# [! W2 E    modelSchedule.at$createAction (0, modelActions);
        
0 S8 d1 j! v' y1 e) S" s4 f& T    return this;
  }