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：
( f% |& G6 o0 k; x( P0 J
: V" b! r8 H$ e# V8 w1 [- | public Object buildActions () {
: r) |8 u$ x! G2 @& L) ^2 a" Y+ }6 p    super.buildActions();
   
    // Create the list of simulation actions. We put these in
0 E6 Y( c, j, u- X  z- X    // 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
" @1 ~0 @2 u& U8 Y+ ~# |! k5 b* L    // diffusion, then run "updateWorld" to actually enact the
    // changes the heatbugs have made. The ordering here is
/ ]6 w( b. Z, J* D    // significant!
        
    // Note also, that with the additional
% ?. V# R) \. ^- p    // `randomizeHeatbugUpdateOrder' Boolean flag we can
    // randomize the order in which the bugs actually run
: Q; ^. `; c& N0 E    // their step rule.  This has the effect of removing any
    // systematic bias in the iteration throught the heatbug
2 ]- K% b- s. X! y- Z' e    // list from timestep to timestep
        
    // By default, all `createActionForEach' modelActions have
$ d# \& {- G* \. p7 j    // 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
" y' j/ ^+ Y2 }! V# @7 L/ D* U    // indirectly by some other process).
1 o/ Q9 W2 A5 k; p) {8 }   
( C7 F  z# ?& |/ H3 N    modelActions = new ActionGroupImpl (getZone ());

    try {
      modelActions.createActionTo$message
6 d+ i6 h. M- ?/ h; K" ]8 \        (heat, new Selector (heat.getClass (), "stepRule", false));
    } catch (Exception e) {
      System.err.println ("Exception stepRule: " + e.getMessage ());
    }
! K2 c" @- B! m6 W5 W
    try {
1 I! \0 U( ^1 i" M5 d8 t      Heatbug proto = (Heatbug) heatbugList.get (0);
      Selector sel =
1 @7 ~; p% @8 I        new Selector (proto.getClass (), "heatbugStep", false);
- H% }5 Z9 D) j) x      actionForEach =
        modelActions.createFActionForEachHomogeneous$call
" k+ Z! u9 H! J$ U6 H        (heatbugList,
  X$ L* v- y4 f3 \+ Y; E. E7 R         new FCallImpl (this, proto, sel,
                        new FArgumentsImpl (this, sel)));
0 r  ]9 v" L5 J/ [    } catch (Exception e) {
      e.printStackTrace (System.err);
    }
  U1 ]. [! d- x8 r  y0 L  J. G   
6 A- M* B& N* i/ ~/ E- l+ e    syncUpdateOrder ();

" p) U) S8 _/ f7 M1 x$ W* J. _, ~    try {
* v. K- Q0 V) M3 U- X      modelActions.createActionTo$message
/ m! V& \% j6 o' m8 a2 U' Z        (heat, new Selector (heat.getClass (), "updateLattice", false));
4 z3 A$ h2 X# ^3 O7 s; d( A    } catch (Exception e) {
      System.err.println("Exception updateLattice: " + e.getMessage ());
8 _- h7 t' t# H4 a. k" D' v  ?    }
        
# L* P( [1 V% ~& G5 y    // 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
    // time, we create a Schedule that says to use the
8 ^) d" J) q) O    // modelActions ActionGroup at particular times.  This
) D) c$ H# z9 H6 r2 m. X' X" m- t$ }    // 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.

. n# E; t5 G, D$ |; w8 q$ J) j    // This is a simple schedule, with only one action that is
    // just repeated every time. See jmousetrap for more
: o. S. d# z9 m9 T, T2 L; y    // complicated schedules.
  
5 M; D2 o, o: Z+ b* D& K    modelSchedule = new ScheduleImpl (getZone (), 1);
    modelSchedule.at$createAction (0, modelActions);
        
; b8 l6 a) H: a: @: F* A    return this;
  }