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：
/ |0 u- }4 \) C3 x
0 k2 k9 q$ M4 B5 `/ F public Object buildActions () {
! h5 E9 i/ Q- y% K6 ?+ e) K$ ]  K    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
+ \' T1 D# x+ x6 |1 I& X    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
. Z. V; }8 ~. ~; J  z' @$ |/ ?! _    // object, or ForEach object in a collection.
$ i  B) [8 f" u: d2 _        
- p, e) V# T" j    // Note we update the heatspace in two phases: first run
    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
% d. F3 B" s3 |    // significant!
        
    // 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
    // systematic bias in the iteration throught the heatbug
8 t* i+ e9 p$ J7 ~    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
5 w5 B2 w/ ]" _" g    // indirectly by some other process).
   
% N4 @4 ]: N& _  d1 z9 i; i    modelActions = new ActionGroupImpl (getZone ());
  ?) m  d+ G% C7 i
    try {
2 n: z- ]) T$ u      modelActions.createActionTo$message
; I5 n5 S5 `4 }8 r        (heat, new Selector (heat.getClass (), "stepRule", false));
; ]7 h" W; ?1 f- L8 e5 Y    } catch (Exception e) {
+ d2 N- \2 p# |3 |( w, z      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
7 @  X8 x" q% r2 r( a
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
# E' E  I& l) e" `, y" `      actionForEach =
) d1 f' b( M/ }' z        modelActions.createFActionForEachHomogeneous$call
3 ?; L9 \' [" ~( K4 u        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
4 E1 W" ]% |6 t) V. }4 @    } catch (Exception e) {
      e.printStackTrace (System.err);
4 s7 S& q% `: t8 L  a% d    }
   
) z6 B+ D$ B# V. n! w' F. ^    syncUpdateOrder ();

/ c4 t+ w  M* ^3 k  B  C. Q    try {
$ |0 e' y! Z+ m      modelActions.createActionTo$message
; m2 ~% P! N) I# k2 h        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 ?  H5 l) A4 N3 q2 U% F. m    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
( Q( B" P+ W1 j. W1 p* J    }
( l7 p% n5 o* {2 @# i9 y        
    // Then we create a schedule that executes the
2 v- Q! d' o9 `; T' U    // modelActions. modelActions is an ActionGroup, by itself it
* h0 G3 z5 D: J    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
, \# G: T- I  Y6 {: S9 n: B    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
    // 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
& p) S, {0 L9 _! K    // just repeated every time. See jmousetrap for more
# q4 Q. c0 v; n* |    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
2 Z1 F# q/ u+ s; v    modelSchedule.at$createAction (0, modelActions);
        
    return this;
+ H, E5 ~$ Y( t) T! L0 m& y8 T: V  }