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：
: Q* {$ W, R! D5 w0 U, S5 d, X5 @6 a
" M, R( W  Z2 `% Q public Object buildActions () {
    super.buildActions();
   
    // Create the list of simulation actions. We put these in
0 J  h2 K/ y0 y    // an action group, because we want these actions to be
    // executed in a specific order, but these steps should
4 J. }( p0 |; |9 W% h1 F1 m1 z    // take no (simulated) time. The M(foo) means "The message
& i8 l8 H( d/ [+ E7 p5 N/ U    // called <foo>". You can send a message To a particular
    // object, or ForEach object in a collection.
( H" l: g( j, c: q: q/ s" M0 }        
5 ]. P  h% Q* Y) G/ n( `/ I    // Note we update the heatspace in two phases: first run
# L4 i3 I. f4 |# K1 [- s0 a    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
) i1 ?0 b$ t8 _0 X    // randomize the order in which the bugs actually run
    // their step rule.  This has the effect of removing any
5 _# q1 b$ P2 f- M2 s  O- R    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
' v0 K! n. d$ f; k! O+ o        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
    // order of iteration through the `heatbugList' will be
1 P# g) |) m$ ~' |' [& e    // identical (assuming the list order is not changed
  R0 a( [$ \# ?1 ?3 k    // indirectly by some other process).
   
    modelActions = new ActionGroupImpl (getZone ());
# B- ~% M/ g& N* o% [6 g7 w3 w! O
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
0 x/ _. F. I. \3 N/ ]& ^      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

( e+ g3 H8 `" F4 z3 Q: I, o    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
) x4 r; |: t. r* L  _3 n      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
8 U  U. y- j7 j6 h! S. m      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
* B  w0 D0 i7 l9 V* g+ g' V        (heatbugList,
9 ^! _# E/ O; ~         new FCallImpl (this, proto, sel,
) d% W, G$ T1 @6 S, ]. Y5 R- K                        new FArgumentsImpl (this, sel)));
8 C' V: }9 F1 E7 F* g    } catch (Exception e) {
      e.printStackTrace (System.err);
8 c8 o# A* N5 _( u! r    }
( ~' x7 v; B3 g# a7 z6 a! {   
$ P: K, L* o. v* }1 B+ w    syncUpdateOrder ();
5 m, }5 B% z0 c5 ~9 r
3 x( l9 M' V# C4 w5 z    try {
; Z& ^8 a! F" _" u# l      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
0 E  H0 c/ Q1 j    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
- s3 }# P$ f/ f$ }) k4 g        
    // Then we create a schedule that executes the
" Q6 L, ]1 {7 O9 z! l  Y* W( Z; _    // modelActions. modelActions is an ActionGroup, by itself it
7 U0 j; z: x, e; o) ^5 D5 y    // has no notion of time. In order to have it executed in
6 z1 S( o& }, ]% G) O. i: _    // time, we create a Schedule that says to use the
    // modelActions ActionGroup at particular times.  This
# S, h6 p. U) [    // 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.
; O8 J3 r1 d) j2 R# {0 g
    // This is a simple schedule, with only one action that is
1 m: P" b2 d( R    // just repeated every time. See jmousetrap for more
    // complicated schedules.
  
/ l7 y: U) d6 r  e& v8 u; @7 c    modelSchedule = new ScheduleImpl (getZone (), 1);
) k+ F/ t' k. ^( D. b! b1 }: M    modelSchedule.at$createAction (0, modelActions);
        
  _) x1 ?2 {, q. T; ]  J% N) a# V8 S    return this;
: x. q  M3 x' \% a; P' g% E1 U; S  }