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：

% S" P: [& K) h) ]. l# [- M4 ] public Object buildActions () {
' ]$ _8 @; U8 a6 y! S    super.buildActions();
0 I9 H2 q' }9 [7 y$ g4 B' T   
6 z+ l1 H, P2 ]+ y+ l# M    // 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.
        
# V6 ]! g; I9 p) ^; }- ]/ |    // Note we update the heatspace in two phases: first run
; _  ^% X+ X, {' i    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
0 A) S& X: d+ e    // significant!
        
    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
! N4 J1 r: `) B    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
    // list from timestep to timestep
& {: y4 J9 J) B' v$ `" [' N        
) M( K  m' L- U% S1 |    // 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).
' Y& F; [3 m8 N  X6 _" M   
" I" b& b  `9 L0 Z! `    modelActions = new ActionGroupImpl (getZone ());

. E" {$ h, |, m  P& P8 Q    try {
      modelActions.createActionTo$message
) I3 N9 {8 M: i        (heat, new Selector (heat.getClass (), "stepRule", false));
/ m1 X! N4 X; u1 z+ J7 O7 ?' ^3 s    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }

3 G& P) |& D  w  l3 H+ z( k& S  E, v, j    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
- ~6 ]5 K% V* V/ |      Selector sel =
        new Selector (proto.getClass (), "heatbugStep", false);
" u& b/ J; |$ c8 H      actionForEach =
) E0 }* ]# y/ p5 ?. L5 y        modelActions.createFActionForEachHomogeneous$call
        (heatbugList,
0 n: X1 b  f; d. V4 W3 \0 i: F         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
    } catch (Exception e) {
      e.printStackTrace (System.err);
6 M" F# F" {( D; z; W) g1 k    }
  m8 F% `, F- U! v, }   
! L2 |7 f) t1 ^2 p0 W    syncUpdateOrder ();
  [( w4 K& b( E6 n1 i* U% e
    try {
      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
# [- ~$ T/ Z+ C6 N# Q. n    } catch (Exception e) {
: S( ~# O2 i# }+ ^5 z- i0 B' f      System.err.println("Exception updateLattice: " + e.getMessage ());
  c% U+ X5 C+ q' Y* K, x    }
        
& U/ L# q1 V; A7 ~    // Then we create a schedule that executes the
9 O4 l( R8 S; U    // modelActions. modelActions is an ActionGroup, by itself it
    // has no notion of time. In order to have it executed in
& l. E. o4 F. y2 z3 D# `- ?$ n    // 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
0 U3 P4 ~, z6 S    // time step.  The action is executed at time 0 relative to
! K8 b  Y: R8 o* B4 o2 L    // the beginning of the loop.
3 F, t3 f2 @- f) t) `
    // This is a simple schedule, with only one action that is
& z% x7 P, K% E" m    // just repeated every time. See jmousetrap for more
    // complicated schedules.
/ M1 `" t4 d" E  
$ i) r$ r! f: P& a' m: U    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
* G, @" X5 I* i4 T# y        
    return this;
& u* c- A2 b9 s7 V# a  }