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：

. G. X1 {( i* }" _# x2 F) P, w public Object buildActions () {
& Z+ H: U$ ]; Z    super.buildActions();
5 p5 `% I: C! ~* ?# i   
    // Create the list of simulation actions. We put these in
3 s& ]3 a! E+ M    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
    // take no (simulated) time. The M(foo) means "The message
% I" }) }& o7 J    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
+ X* K" [& q" z+ V1 R+ l        
    // 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
' _7 P; _# S8 v. P! o+ a1 U* B    // significant!
, B6 a$ ]* F* z( d" ]5 L6 [        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
* J. P; V; E& Z, d) s    // 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
        
7 R# h) y4 H) M( p- h    // 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).
/ _0 z* F9 w! N& d   
. a, ^9 w: c. t" u$ }0 e* N    modelActions = new ActionGroupImpl (getZone ());
: D0 X2 }( G( k; T
0 `* p) w* V( Z+ F0 z: \  U6 E- p: I9 V    try {
0 @, v) ^( `; Z* r/ `( j      modelActions.createActionTo$message
1 U# ~; B( r& Z2 G4 S( n        (heat, new Selector (heat.getClass (), "stepRule", false));
4 F* y0 Z& [0 m2 U& y& i5 h    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

( p0 i% g( z+ T4 f    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
. W: j0 C2 S# a6 Y+ v- l( ~      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
# ^7 `2 D7 x7 G/ L  V        (heatbugList,
         new FCallImpl (this, proto, sel,
* i# O# P! ^# p: Z9 _, D% K                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
) B/ X; S* H; ]. b/ |      e.printStackTrace (System.err);
    }
   
) Z" B* z+ y0 w5 h6 g6 z+ x9 m7 v    syncUpdateOrder ();
% y8 ]7 H! W- |# @
. b* g; _- K- D. ~3 f) i4 {    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
9 B2 E# [" D; u. n    } catch (Exception e) {
8 ~* w" i, n, X4 Y! G      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
' |# q2 N' d5 o5 K4 I    // Then we create a schedule that executes the
6 s6 }, l- g" `; ]9 p& n1 T# B    // 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
/ }; \! C# l6 y0 `    // modelActions ActionGroup at particular times.  This
9 L- D+ _% E' u    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
9 r4 U/ p5 k: F; W    // 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.
) d7 Q1 q5 {' x- R" O! `: q  
7 }$ y. H" w: k' M% p( P: }    modelSchedule = new ScheduleImpl (getZone (), 1);
* M0 x& s+ q$ s2 L$ r8 n  v$ O) _    modelSchedule.at$createAction (0, modelActions);
6 c/ Z- \( t& [0 m        
    return this;
2 R# e) ~) @8 h, C% L+ m# v- v  }