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：
, W* w. ^4 H. U& R
; a: F8 y2 W- M! ?0 G public Object buildActions () {
6 z2 v6 X9 U+ U4 u9 S0 V    super.buildActions();
" h8 A6 d3 D+ ?) }   
* p: p. m: u' }# d% X    // 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
    // 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.
        
    // 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
    // significant!
5 v; r: g# e$ O' Z3 u        
    // Note also, that with the additional
1 N* k% J: s2 m& w    // `randomizeHeatbugUpdateOrder' Boolean flag we can
" _" v$ r, u8 i) z) w# t    // randomize the order in which the bugs actually run
/ ]% n# q0 u) z- U; l; A    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
' a0 O6 Z0 k5 v        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
, N) l7 J8 m/ _4 X* ^    // identical (assuming the list order is not changed
; c8 h2 {4 e) i0 l9 V4 }2 R3 g    // indirectly by some other process).
   
; I3 F# q$ B! I    modelActions = new ActionGroupImpl (getZone ());
. k3 `' o+ G+ z2 a- D  F
8 k/ S- ]2 R; \# J% Q" ^7 x    try {
      modelActions.createActionTo$message
0 v6 C% M, B) [! R3 s* g$ T/ i        (heat, new Selector (heat.getClass (), "stepRule", false));
$ g) Y- C+ M' L3 U, U    } catch (Exception e) {
) K- M3 m3 p* d7 H: T# e      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

    try {
* u. R( c  q) w4 ~7 {      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
! {6 N* }  P" o0 p- {7 s3 {        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
         new FCallImpl (this, proto, sel,
6 l) }% ?2 R- V) X" M                        new FArgumentsImpl (this, sel)));
) e& T5 Q1 T! ?" I* J, |    } catch (Exception e) {
# j4 ?- X9 u# d* ~      e.printStackTrace (System.err);
( x7 L0 [: l7 L. ]# d    }
   
7 b+ s: e0 I2 n, g* @7 b. T1 ^    syncUpdateOrder ();
$ |# t& z+ w3 e# b
  h) F. }8 g* l: I9 J5 o    try {
      modelActions.createActionTo$message
+ F( o1 C- J6 c2 @        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
# Q. w; X" B- q; A5 p4 _    }
. S- n. Q0 a4 m2 s7 v  b        
0 d7 c8 D; p5 l2 `    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
: I5 [. _6 t: o$ g    // time, we create a Schedule that says to use the
% l8 ]( h3 Z( b/ c* O    // modelActions ActionGroup at particular times.  This
2 B$ C* [, `7 q0 r6 Q% Z& e    // 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.
, w; P, ~  d; a) [* s$ C5 x
    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
! I: p/ M% ]* p5 Q    // complicated schedules.
  
4 n2 X* q. L9 c' Y    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
    return this;
  }