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 () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
5 I4 Q6 z1 B9 Z$ w    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
4 u7 b' V) ?, J9 z2 b$ P    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
2 L+ I- ?3 ?- }" l5 q/ P" k' L    // object, or ForEach object in a collection.
8 [, y2 g0 Z5 M/ b" T5 u8 {        
, {: n  H( G* G: H    // Note we update the heatspace in two phases: first run
# P' t" `; ~& M; R* t: i    // diffusion, then run "updateWorld" to actually enact the
7 O# j' L; F, {. I2 `) s    // changes the heatbugs have made. The ordering here is
    // significant!
        
' l1 ]6 ~+ N4 j0 O6 N& O    // 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
% C$ o6 M4 X6 m2 X8 S* s; J7 z    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
0 {: }9 X2 d8 H. i; }    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
8 g. d! l, |- ]8 d& Q1 P    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
   
1 \  M8 n, s7 M5 X2 {  M    modelActions = new ActionGroupImpl (getZone ());

$ G& c1 J+ E. @    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
& A- }! J4 |' l: T. F0 w# B# i    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
8 L( ?9 E% H. V2 ]2 g3 u7 g    }
% ]1 C1 g: F$ W* s0 R
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
! |! [5 P$ E$ a: s" P# s      Selector sel =
( c2 S$ q- ~" u# q, W        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
$ D4 U" x( D. }) H, A        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
# f7 `8 f; w+ o! z/ {    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
# {+ X  l0 c) o% ^0 S1 a    syncUpdateOrder ();
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    try {
      modelActions.createActionTo$message
" `2 G' J1 q5 U0 X7 V0 c        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
+ D5 E5 a+ i! U6 O2 }) J# @9 H1 V        
* `0 m! n" Y; B: O+ l7 g! W) L5 @, H    // Then we create a schedule that executes the
& f% c( p& B- R" x    // modelActions. modelActions is an ActionGroup, by itself it
- O3 b' e) C! v; e- I7 e. E    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
9 d( C: G! K  U9 Y/ Y$ I: Y, }    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
! k, i0 F4 v3 ~' W1 B2 u' W$ D    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
0 O! Q4 I! F0 O2 q# T4 t4 H; m. A    // just repeated every time. See jmousetrap for more
) a6 e3 h3 ~, Z$ \+ _$ a0 @    // complicated schedules.
* u  I4 Z" G, h7 g4 q% C0 L- j  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
& S1 R/ ~% v3 B7 N7 R" l    return this;
! f# H! y# }2 _  }