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：
8 t: z) E% \, s: O  {
public Object buildActions () {
0 a2 o! R* t- ]) H  ~0 s+ o% C    super.buildActions();
   
    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
+ a& f: |) e7 W' E. ?) I" p% k8 ^    // 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
    // object, or ForEach object in a collection.
        
, z/ F+ q3 a4 d    // Note we update the heatspace in two phases: first run
. k- l% A) I) Z5 T" \' ]4 y# u    // diffusion, then run "updateWorld" to actually enact the
5 @) S/ \; h2 p% N    // changes the heatbugs have made. The ordering here is
    // significant!
2 P7 k2 R8 U) P% @# T        
3 z+ F7 `* R' f: q    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
0 w: A: S7 ~/ K, X( u. q    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
8 T6 e, c$ N5 E" d8 s, ]) d    // list from timestep to timestep
% R8 e6 E) u; H/ d5 @        
" o( u% G4 i5 [2 u7 J+ }$ F% L    // 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
    // indirectly by some other process).
   
1 a2 \1 {8 ]8 H, i' |    modelActions = new ActionGroupImpl (getZone ());
0 x# {" b, K+ h. ]" l& i' F1 ^+ O
* b4 e9 F: s# X; n- Y! W# K    try {
  m4 \( {9 P. P      modelActions.createActionTo$message
& c4 T5 I3 x1 Z0 D$ k3 ?        (heat, new Selector (heat.getClass (), "stepRule", false));
. `, Q8 ]( \4 ?    } catch (Exception e) {
; P7 O" X9 w$ P  u# F      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
9 p/ J2 u- ~$ X( ~# N) @* y
    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
+ p4 k0 ^# R3 p$ v& u6 J' m2 C. X      Selector sel =
3 P) Q; r7 u% Q- z, e; A# F1 |        new Selector (proto.getClass (), "heatbugStep", false);
8 y7 }. V: \( i/ R# t      actionForEach =
8 v' n$ h0 y3 e        modelActions.createFActionForEachHomogeneous$call
; X) j5 N4 a. K7 k" m% J: z        (heatbugList,
+ I4 e/ f: Z1 ?$ J' B2 x         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
   
: o3 \6 t! t- e" M4 K$ H    syncUpdateOrder ();

) _  G/ G. p3 K' L    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
" W' g% P3 q9 x& ?    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
) I8 a' L! G. h- O8 ?2 f    // has no notion of time. In order to have it executed in
) M. y, B/ I! W/ A6 U    // time, we create a Schedule that says to use the
+ V% \# _% M; B. @    // modelActions ActionGroup at particular times.  This
    // schedule has a repeat interval of 1, it will loop every
8 M7 X, |  |3 H+ N/ d* r/ m6 c+ `    // 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
) y. @: u# x0 N( R4 ^/ R    // complicated schedules.
  
: O- a& s6 [/ V: X- G( P7 r4 Y    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
3 `6 H/ H) c1 `  b! f7 ^    return this;
  }