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：
' @; o- G- U" j/ m
public Object buildActions () {
    super.buildActions();
' R% e) \0 H/ J) w   
( t8 t6 x/ g! B, f: {& ^) r! r    // Create the list of simulation actions. We put these in
    // an action group, because we want these actions to be
& f! v& ?2 P9 L" l: L    // executed in a specific order, but these steps should
& i! O/ a! Y3 b% X- Z    // take no (simulated) time. The M(foo) means "The message
    // called <foo>". You can send a message To a particular
2 Z* b" W8 }2 e, W, S) V    // object, or ForEach object in a collection.
4 E+ A5 o6 f) m" |/ v        
0 _. A0 f/ G# `1 W$ Y. E    // 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
# ^/ Q. v3 N% C2 o: m- l- k    // significant!
        
/ A3 K& t& ^- n% J    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
( d) q+ V0 R9 B. e    // randomize the order in which the bugs actually run
/ P" W0 T$ M1 |. Q    // their step rule.  This has the effect of removing any
6 M9 w9 G( \3 }. L/ c  H: H    // systematic bias in the iteration throught the heatbug
) ]& _+ }8 c( A    // list from timestep to timestep
5 b* ~7 A/ N+ r" k  J$ A        
    // By default, all `createActionForEach' modelActions have
. [# \7 Z5 R2 X1 f* d$ T    // 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
6 F; F+ u: l4 K) V- h% \    // indirectly by some other process).
   
4 A8 f* B/ l2 u1 w" f) o5 m1 g0 f    modelActions = new ActionGroupImpl (getZone ());

    try {
9 O$ g: s" x% U      modelActions.createActionTo$message
, D2 b/ p9 r  S' l        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

# c. L) L9 U# b3 X9 i+ {% q    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
+ L1 I4 y" Q2 ^/ H$ G% S; w3 G      actionForEach =
, M# f, Q8 X+ r5 P. Z' S+ K" I2 s, q        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
1 V9 b  O' n3 C                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
6 }: l4 I5 {3 s9 M5 {" E, a      e.printStackTrace (System.err);
, B: i2 e# U) x* _) J! _# g  o7 \    }
& |$ L5 `! ~+ m0 ]  O   
8 z0 Q5 s5 N+ n5 N    syncUpdateOrder ();

    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
6 @4 A* d& T1 s. M& U9 o    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
6 c9 }6 }4 f  C  X    }
        
    // Then we create a schedule that executes the
    // 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
    // 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
5 n1 R/ Q- |5 t; ?    // just repeated every time. See jmousetrap for more
' {9 B6 s# G- P5 ?- x$ j. S6 m& ^    // complicated schedules.
  
    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }