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：
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public Object buildActions () {
8 c! f9 _; q! n' `1 H    super.buildActions();
   
    // 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
. I6 W3 T# w4 _, q6 m2 ?    // called <foo>". You can send a message To a particular
4 d1 F3 e! u9 n: x# a" M    // object, or ForEach object in a collection.
) c1 ^- K" F5 w/ j        
    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
- T; z) H! W) t, i, r+ A    // changes the heatbugs have made. The ordering here is
# ~* u2 K7 L" n) J7 j    // significant!
% n2 t& r3 y) o+ m" A* r, E        
6 }4 e# J( g5 F- \& M2 r    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
$ n; X+ L2 L* \! e% e* a1 U    // systematic bias in the iteration throught the heatbug
( B! A, l% t) ^9 v1 W; H    // list from timestep to timestep
        
' z2 g0 z  C2 J. F7 ?0 ]2 T    // By default, all `createActionForEach' modelActions have
" f; U8 g5 s+ N3 b/ a9 r9 A    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
; t7 j0 f, i8 H- e: F+ p& G    // identical (assuming the list order is not changed
    // indirectly by some other process).
% P+ M0 B' \* t3 w0 r- d   
    modelActions = new ActionGroupImpl (getZone ());

/ a2 z4 V6 N* q) w! M    try {
$ G! n6 S& q! w* W) V+ J0 N# J      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
( P* b8 o* ^& U7 e4 t2 g    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
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    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
2 c/ x. Y5 B! C3 ]# f1 ~7 k      Selector sel =
) V2 Y  M% ~3 H        new Selector (proto.getClass (), "heatbugStep", false);
8 C2 {- i4 l5 t* F3 Z6 B6 |; H      actionForEach =
/ k" w5 \% o6 @, ~        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
2 N1 T+ ~3 k1 G* D# V2 }" ]                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
) }" o; Q: {- w      e.printStackTrace (System.err);
    }
! H3 R0 b1 g; }! E. _1 i+ j" K" t3 A   
3 @5 [; Z; Y5 h7 D- J    syncUpdateOrder ();

5 ]( w1 I  T2 T9 `    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
3 H5 Y  O7 @( f/ O, o+ F1 J: R2 G% T    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
/ f8 f2 U! |9 s" V- V    }
- `% q$ C# L/ b& |5 |% l        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
, x5 y; ^/ d, c$ L) ~    // has no notion of time. In order to have it executed in
. y1 R* k% j( K3 c    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
* M0 W1 e! N# E4 Q, V    // schedule has a repeat interval of 1, it will loop every
# b8 B9 g1 e. l0 V& M    // time step.  The action is executed at time 0 relative to
    // the beginning of the loop.

, f3 b" B- h, v3 s    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
    // complicated schedules.
7 j( F" h' X6 u- X8 x" h  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
5 K, ^3 b0 t, q4 s        
; ]1 A9 P2 u* t* x& q    return this;
4 ^9 W. B+ A1 _- Z- Z$ Y  }