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：
) Z% x! N' q5 o$ V# \! N0 b. C) z
9 C3 @1 a+ e; P# k0 `- Q+ h( { public Object buildActions () {
& C( B& S! r0 J    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
/ k, `, r  E$ P" l+ _$ [, [    // executed in a specific order, but these steps should
9 M5 {7 Z% A- t4 g6 m    // 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.
  w- ~% y% Z, O4 R        
+ e; q% ]6 O! N* X% A* |5 V    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
0 Q( h% e8 v  U    // changes the heatbugs have made. The ordering here is
    // significant!
" r. y  ~* u- J( p        
    // Note also, that with the additional
# }9 b6 V2 ?; v* Q+ _, D: f    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
    // list from timestep to timestep
        
5 Y5 R) u! p* J* ~$ W9 V    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
. Y% Q# {3 [* p( G    // order of iteration through the `heatbugList' will be
; X% F: U. t- z2 X5 D+ D' Y9 o. R    // identical (assuming the list order is not changed
  b0 w8 D0 k8 r; R1 V* \% L    // indirectly by some other process).
7 |0 u- l3 U! R' f/ p1 Q3 p" }   
    modelActions = new ActionGroupImpl (getZone ());
( r2 J) S+ t3 N4 w/ I
/ z: y& Q4 D; l* b7 e2 z# s    try {
6 m* b+ J) {+ Z+ b3 x( C# ^      modelActions.createActionTo$message
) Y4 K9 n% Y/ t  P! k) Q  L; r- }        (heat, new Selector (heat.getClass (), "stepRule", false));
8 u: z8 H+ w2 r+ k5 s    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
- b4 L( S( X- N* u1 w0 h( ]7 L    }

    try {
3 b, \4 [. |2 U9 Y, `, T8 x, ]3 Q      Heatbug proto = (Heatbug) heatbugList.get (0);
' a( P7 g; v  j- m      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
" ~8 C/ I0 C: F; I, W" O: ~7 w        modelActions.createFActionForEachHomogeneous$call
  ]* z7 K) C$ G+ j! m        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
% e7 y6 v% \- W; m% @  z      e.printStackTrace (System.err);
    }
   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
! q& a$ I+ N! Q2 B) B    } catch (Exception e) {
1 L+ v9 x' o0 v: X! [5 [+ U      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
' J/ X% U. f6 C    // 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
    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
( x& Z$ C! @/ _* u% O5 Z8 f    // 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
    // complicated schedules.
6 s$ `) @3 B! v  b8 R) ]7 e  
/ |  @+ e; W% V! i    modelSchedule = new ScheduleImpl (getZone (), 1);
2 F7 w' @  Z3 c: r/ N) M    modelSchedule.at$createAction (0, modelActions);
        
6 L: b5 s: [  a    return this;
) G% B0 X+ d1 q5 R" X2 h  }