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：

. ]4 @, u1 I0 h# J: z: ?1 ~) ^ public Object buildActions () {
    super.buildActions();
   
( q1 i1 T' F* t) X  K0 ]6 R    // 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
% C5 {& J$ A2 R2 k    // 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.
4 v) ]& {* Y; G9 G* O        
    // Note we update the heatspace in two phases: first run
3 T) V, _" c3 v    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
: {2 |% x) f- V% U    // significant!
' C* H6 Z! P8 M9 U        
' @' J/ t9 ?+ e6 Z: N$ V    // Note also, that with the additional
    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // 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
        
    // By default, all `createActionForEach' modelActions have
    // a default order of `Sequential', which means that the
* a( }" {. E2 I. {5 w8 {    // order of iteration through the `heatbugList' will be
    // identical (assuming the list order is not changed
    // indirectly by some other process).
4 d$ ?  V# t! C3 f9 R   
, i' }: c: j" y. l    modelActions = new ActionGroupImpl (getZone ());
! \; N" @5 X" @2 D5 S# c
    try {
      modelActions.createActionTo$message
  w# \5 l% s2 a9 U9 i/ @' p% w        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
$ @  n1 u$ ^  |' ^
- D4 O% y$ e: l) ?$ T6 [0 v& v    try {
      Heatbug proto = (Heatbug) heatbugList.get (0);
8 d1 E6 i6 |, b' Q# b9 J# a9 `      Selector sel =
6 d" w+ H1 K0 i% ]        new Selector (proto.getClass (), "heatbugStep", false);
      actionForEach =
! e. z* {0 h2 q' r5 q$ d2 _; E' s/ R        modelActions.createFActionForEachHomogeneous$call
. k; C) s" G/ f9 W        (heatbugList,
         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
* v9 u8 b% x1 {" V# ~    } catch (Exception e) {
      e.printStackTrace (System.err);
/ c$ F; D2 J" u2 q  x: p' ]" C; E    }
   
    syncUpdateOrder ();
8 b7 I& ]9 V. d' V% b* v/ u
    try {
9 ?3 `" R0 J5 O+ M/ S+ t% c      modelActions.createActionTo$message
        (heat, new Selector (heat.getClass (), "updateLattice", false));
    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
    }
        
    // Then we create a schedule that executes the
    // modelActions. modelActions is an ActionGroup, by itself it
/ W) }% k4 Q  M# F4 W    // has no notion of time. In order to have it executed in
    // time, we create a Schedule that says to use the
- D6 ?5 I  Z3 U( a- `  k! V+ u    // modelActions ActionGroup at particular times.  This
  S) x: Q* T0 m, {. d5 r) r2 R    // schedule has a repeat interval of 1, it will loop every
    // time step.  The action is executed at time 0 relative to
: o3 k6 Z' K* ]    // the beginning of the loop.

; L: t8 a' }# N' i! Q    // This is a simple schedule, with only one action that is
2 H1 n* W% h1 c# K    // just repeated every time. See jmousetrap for more
9 v) L6 b$ J, {) {    // complicated schedules.
  
5 p$ R, v: f5 B6 M3 P9 T    modelSchedule = new ScheduleImpl (getZone (), 1);
& l4 y2 z2 E: L, t5 }0 E    modelSchedule.at$createAction (0, modelActions);
        
    return this;
* }% ~0 Q3 E8 r% N  }