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：

+ f+ {: c4 C2 v3 C9 ~/ o) \( Y1 q public Object buildActions () {
    super.buildActions();
   
/ p$ N4 l$ B0 F2 Q    // 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
$ Y. i) d9 e( M! V# f    // 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.
        
9 Y. p5 P7 O8 ^2 }& ?) c    // Note we update the heatspace in two phases: first run
3 t" S9 h8 @8 z4 y9 l( i" F    // diffusion, then run "updateWorld" to actually enact the
$ a; ~0 Z* V& O: `# }! B% c    // changes the heatbugs have made. The ordering here is
+ p3 M; F, W+ e3 y# a: s/ C% W( c    // 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
0 m; O- j0 a8 c% S1 L    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
! x$ g" F, v6 \, J, G7 K# g    // order of iteration through the `heatbugList' will be
) D% G' t# ^" t# D4 X    // identical (assuming the list order is not changed
; V0 X! _1 y8 O7 ]/ ^9 }    // indirectly by some other process).
7 {' a5 v- F) h% a: P   
    modelActions = new ActionGroupImpl (getZone ());
, O( f0 V- J5 R4 V  j" c, z
    try {
! U/ P! M3 R; \+ w; V+ y      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

) _- Q' C! _( G# z    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
, I$ s1 n, U! w- Y3 a, z      Selector sel =
8 {% I2 @4 x1 w2 g; h. Y1 e& W        new Selector (proto.getClass (), "heatbugStep", false);
* q7 E, T; B, F      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
- Z/ R$ X, D0 V, J, N: A6 g& l                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
; M" m) Q* B6 s) d& J% j- k5 C      e.printStackTrace (System.err);
  ?1 o9 C8 ^" W2 Y    }
   
    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
, o7 g' C4 ?3 h5 M        (heat, new Selector (heat.getClass (), "updateLattice", false));
+ P1 Q! j5 [+ [5 E2 I' C    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
/ t: i2 N1 b5 q2 R! ?* n    // modelActions. modelActions is an ActionGroup, by itself it
$ c4 r) ~. G$ G4 T    // has no notion of time. In order to have it executed in
$ w6 \+ w% }: W7 W; X    // 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
6 X3 d5 ]2 u- J. U    // time step.  The action is executed at time 0 relative to
) C+ |2 T! |, K) M3 w    // the beginning of the loop.

    // This is a simple schedule, with only one action that is
; x# k, v( B% }    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
6 {+ T9 i2 H; h  X    return this;
  }